feat(preprod): Perform actual extras column drop (#93466)

Second step of the plan in
#93388

Won't merge until the first PR is fully deployed.

Author: trevor-e

migrations_lockfile.txt

@@ -19,7 +19,7 @@ monitors: 0006_add_is_upserting
 
 nodestore: 0001_squashed_0002_nodestore_no_dictfield
 
-preprod: 0002_drop_sentry_jsonfield
+preprod: 0003_drop_sentry_jsonfield_actual
 
 replays: 0001_squashed_0005_drop_replay_index
 

src/sentry/preprod/migrations/0003_drop_sentry_jsonfield_actual.py

@@ -0,0 +1,31 @@
+from sentry.new_migrations.migrations import CheckedMigration
+from sentry.new_migrations.monkey.fields import SafeRemoveField
+from sentry.new_migrations.monkey.state import DeletionAction
+
+
+class Migration(CheckedMigration):
+    # This flag is used to mark that a migration shouldn't be automatically run in production.
+    # This should only be used for operations where it's safe to run the migration after your
+    # code has deployed. So this should not be used for most operations that alter the schema
+    # of a table.
+    # Here are some things that make sense to mark as post deployment:
+    # - Large data migrations. Typically we want these to be run manually so that they can be
+    #   monitored and not block the deploy for a long period of time while they run.
+    # - Adding indexes to large tables. Since this can take a long time, we'd generally prefer to
+    #   run this outside deployments so that we don't block them. Note that while adding an index
+    #   is a schema change, it's completely safe to run the operation after the code has deployed.
+    # Once deployed, run these manually via: https://develop.sentry.dev/database-migrations/#migration-deployment
+
+    is_post_deployment = False
+
+    dependencies = [
+        ("preprod", "0002_drop_sentry_jsonfield"),
+    ]
+
+    operations = [
+        SafeRemoveField(
+            model_name="preprodartifact",
+            name="extras",
+            deletion_action=DeletionAction.DELETE,
+        ),
+    ]