feat: promote StepActions to GA

Upgrade StepActions feature from beta to stable to make sure that it is enabled by default.
StepActions has been in beta for a while and is also has good adoption among the community.
It is pretty stable as a feature based on the regular usage. Moving it to GA will make sure
that users will have access to better pipeline composability from the get-go.
The following changes were made:
- set enable-step-actions to "true" by default
- updated to reflect that StepActions are now enabled by default
- changed the feature flag stability from BetaAPIFields to StableAPIFields in feature_flags.go
- updated feature flags, e2e tests and test data
- moved relevant examples to stable examples
- added relevant documentation for the move from beta to stable

This change makes StepActions a stable, first-class feature in Tekton Pipelines.

Author: waveywaves

config/config-feature-flags.yaml

@@ -124,9 +124,8 @@ data:
   keep-pod-on-cancel: "false"
   # Setting this flag to "true" will enable the CEL evaluation in WhenExpression
   enable-cel-in-whenexpression: "false"
-  # Setting this flag to "true" will enable the use of StepActions in Steps
-  # This feature is in preview mode and not implemented yet. Please check #7259 for updates.
-  enable-step-actions: "false"
+  # StepActions are stable and enabled by default. Setting this flag to "false" will disable the use of StepActions in Steps.
+  enable-step-actions: "true"
   # Setting this flag to "true" will enable the use of Artifacts in Steps
   # This feature is in preview mode and not implemented yet. Please check #7693 for updates.
   enable-artifacts: "false"

docs/additional-configs.md

@@ -406,15 +406,14 @@ Features currently in "beta" are:
 | [Isolated `Step` & `Sidecar` `Workspaces`](./workspaces.md#isolated-workspaces)                       | [TEP-0029](https://github.com/tektoncd/community/blob/main/teps/0029-step-workspaces.md)                 | [v0.24.0](https://github.com/tektoncd/pipeline/releases/tag/v0.24.0) | [v0.50.0](https://github.com/tektoncd/pipeline/releases/tag/v0.50.0) |                               |
 | [Matrix](./matrix.md)                                                                                 | [TEP-0090](https://github.com/tektoncd/community/blob/main/teps/0090-matrix.md)                          | [v0.38.0](https://github.com/tektoncd/pipeline/releases/tag/v0.38.0) | [v0.53.0](https://github.com/tektoncd/pipeline/releases/tag/v0.53.0) |                               |
 | [Task-level Resource Requirements](compute-resources.md#task-level-compute-resources-configuration)   | [TEP-0104](https://github.com/tektoncd/community/blob/main/teps/0104-tasklevel-resource-requirements.md) | [v0.39.0](https://github.com/tektoncd/pipeline/releases/tag/v0.39.0) | [v0.53.0](https://github.com/tektoncd/pipeline/releases/tag/v0.53.0) |                               |
-| [Reusable Steps via StepActions](./stepactions.md)                                                           | [TEP-0142](https://github.com/tektoncd/community/blob/main/teps/0142-enable-step-reusability.md)                     | [v0.54.0](https://github.com/tektoncd/pipeline/releases/tag/v0.54.0) | `enable-step-actions`                            |
 | [Larger Results via Sidecar Logs](#enabling-larger-results-using-sidecar-logs)                               | [TEP-0127](https://github.com/tektoncd/community/blob/main/teps/0127-larger-results-via-sidecar-logs.md)             | [v0.43.0](https://github.com/tektoncd/pipeline/releases/tag/v0.43.0) | [v0.61.0](https://github.com/tektoncd/pipeline/releases/tag/v0.61.0) | `results-from`                                   |
 | [Step and Sidecar Overrides](./taskruns.md#overriding-task-steps-and-sidecars)                               | [TEP-0094](https://github.com/tektoncd/community/blob/main/teps/0094-specifying-resource-requirements-at-runtime.md) | [v0.34.0](https://github.com/tektoncd/pipeline/releases/tag/v0.34.0) |                                                  | [v0.61.0](https://github.com/tektoncd/pipeline/releases/tag/v0.61.0)  | |
 | [Ignore Task Failure](./pipelines.md#using-the-onerror-field)                                                | [TEP-0050](https://github.com/tektoncd/community/blob/main/teps/0050-ignore-task-failures.md)                        |    [v0.55.0](https://github.com/tektoncd/pipeline/releases/tag/v0.55.0)                                                              | [v0.62.0](https://github.com/tektoncd/pipeline/releases/tag/v0.62.0)                                                 | N/A |
 
 ## Enabling larger results using sidecar logs
 
 **Note**: The maximum size of a Task's results is limited by the container termination message feature of Kubernetes,
-as results are passed back to the controller via this mechanism. At present, the limit is per task is “4096 bytes”. All
+as results are passed back to the controller via this mechanism. At present, the limit is per task is "4096 bytes". All
 results produced by the task share this upper limit.
 
 To exceed this limit of 4096 bytes, you can enable larger results using sidecar logs. By enabling this feature, you will

docs/stepactions.md

@@ -21,8 +21,8 @@ weight: 201
   - [Controlling Step Execution with when Expressions](#controlling-step-execution-with-when-expressions)
 
 ## Overview
-> :seedling: **`StepActions` is an [beta](additional-configs.md#beta-features) feature.**
-> The `enable-step-actions` feature flag must be set to `"true"` to specify a `StepAction` in a `Step`.
+> **`StepActions` is a stable feature.**
+> Step actions are enabled by default. You can disable them by setting the `enable-step-actions` feature flag to `"false"`.
 
 A `StepAction` is the reusable and scriptable unit of work that is performed by a `Step`.