fix(autofix): Skip code-changes-completed event when PR is created

When webhook_action_type is PR_CREATED, the on_completion_hook was firing
AiAutofixCodeChangesCompletedEvent (from STEP_CONFIGS) alongside
AiAutofixPrCreatedCompletedEvent. This inflated code-changes-completed
analytics counts because the hook also fires after PR creation via
push_changes' on_completion_hook payload.

Gate the STEP_CONFIGS completed_event recording on
webhook_action_type != PR_CREATED so only the PR-created event fires
in that path.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Agent transcript: https://claudescope.sentry.dev/share/pZN9EjD2NnKcBxKbvdo8ab42Yrd8eKMf_wauRcylSb0

Author: chromy

src/sentry/seer/autofix/on_completion_hook.py

@@ -238,7 +238,11 @@ def _send_step_webhook(
                 "autofix.explorer.complete", tags={"step": current_step.value, "referrer": referrer}
             )
             completed_event_cls = STEP_CONFIGS[current_step].completed_event
-            if completed_event_cls is not None and referrer is not None:
+            if (
+                completed_event_cls is not None
+                and referrer is not None
+                and webhook_action_type != SeerActionType.PR_CREATED
+            ):
                 analytics.record(
                     completed_event_cls(
                         organization_id=organization.id,