fix: tfs external ids

[cka-y]

Summary:
Relates to #1463
This pull request introduces improvements to how the operational status and external IDs are managed for transitfeeds in the data import process, and ensures database consistency for existing feeds. The main changes are focused on updating feed metadata and maintaining accurate external ID associations.

Feed metadata management:

• In sync_transitfeeds.py, the code now sets the operational_status of each feed to "published" during processing, ensuring all imported feeds reflect their correct status.
• The logic for associating external IDs has been updated to check if a transitfeeds external ID already exists for a feed. If it does, a debug message is logged; if not, the external ID is added to the feed.

Database consistency:

• A new SQL migration (feat_1249-3.sql) updates all feeds with a stable_id starting with tfs- to set their operational_status to "published", ensuring existing records are consistent with the new import logic.

Please make sure these boxes are checked before submitting your pull request - thanks!

• Run the unit tests with ./scripts/api-tests.sh to make sure you didn't break anything
• Add or update any needed documentation to the repo
• Format the title like "feat: [new feature short description]". Title must follow the Conventional Commit Specification(https://www.conventionalcommits.org/en/v1.0.0/).
• Linked all relevant issues
• Include screenshot(s) showing how this pull request works and fixes the issue(s)

[Copilot]

Pull request overview

This pull request aims to improve the management of operational status and external IDs for transitfeeds data imports, along with a database migration to ensure consistency for existing feeds. However, there are several critical issues that need to be addressed before merging.

Key Changes

• Sets operational_status to "published" for all transitfeeds imports in the Python import script
• Adds logic to check for existing transitfeeds external IDs before adding new ones
• Includes SQL migration to update existing tfs-prefixed feeds to published status

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
liquibase/changes/feat_1249-3.sql	SQL migration to set operational_status for transitfeeds feeds - contains potential pattern matching issue
functions-python/tasks_executor/src/tasks/data_import/transitfeeds/sync_transitfeeds.py	Updates external ID and operational_status logic - contains critical bug that replaces all external IDs

Critical Issues Found:

1. External ID Bug (Line 110-114): The code replaces ALL existing external IDs instead of appending the transitfeeds external ID, which will cause data loss if feeds have external IDs from other sources (transitland, jbda, etc.)
2. SQL Migration Pattern (Line 4): The WHERE clause uses 'tfs-%' pattern, but all evidence suggests transitfeeds feeds use 'mdb-%' prefix, which means the migration may not update any records
3. Missing Test Coverage: The new operational_status behavior and external ID preservation logic are not covered by existing tests