Add error handling for missing gitlab_webhook table

Adds defensive error handling in install_gitlab_webhooks.py to catch
table not found errors and provide clear, actionable error messages.

Root Cause:
- Migration 027 created table as 'gitlab-webhook' (with hyphen)
- SQLAlchemy model expects 'gitlab_webhook' (with underscore)
- Migration 032 fixes this but may not be applied in all environments

This change:
- Catches UndefinedTableError when querying gitlab_webhook table
- Logs clear error message indicating migration 032 is needed
- Returns gracefully to prevent continuous error logging
- Provides actionable guidance: 'alembic upgrade head'

Impact:
- Prevents cronjob from crashing repeatedly in Datadog
- Makes it immediately clear to operators what action is needed
- Reduces noise in error logs

Fixes error seen in Datadog logs since Oct 13, 2025:
  relation "gitlab_webhook" does not exist

Co-authored-by: openhands <openhands@all-hands.dev>

enterprise/sync/install_gitlab_webhooks.py

@@ -262,7 +262,24 @@ class VerifyWebhookStatus:
         webhook_store = await GitlabWebhookStore.get_instance()
 
         # Load chunks of rows that need processing (webhook_exists == False)
-        webhooks_to_process = await self.fetch_rows(webhook_store)
+        try:
+            webhooks_to_process = await self.fetch_rows(webhook_store)
+        except Exception as e:
+            # Check if this is a table not found error (likely due to missing migration)
+            if 'does not exist' in str(e) and ('gitlab_webhook' in str(e) or 'gitlab-webhook' in str(e)):
+                logger.error(
+                    'gitlab_webhook table does not exist. This usually means database migration 032 '
+                    'or later has not been applied. Please run database migrations: alembic upgrade head',
+                    extra={
+                        'error_type': type(e).__name__,
+                        'error_message': str(e),
+                        'migration_needed': '032_add_status_column_to_gitlab_webhook.py',
+                    },
+                )
+                # Return early to avoid continuous error logging
+                return
+            # Re-raise other exceptions
+            raise
 
         logger.info(
             'Processing webhook chunks',