Cadence Test Framework docs include invalid syntax

### Current Behavior

The [Test Framework](https://cadence-lang.org/docs/testing-framework) docs currently have outdated/invalid syntax (e.g. `let blockchain = Test.newEmulatorBlockchain()`).

### Expected Behavior

Update this and any other code issues

### Steps To Reproduce

n/a

### Environment

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### What are you currently working on that this is blocking?

_No response_