feat: Report database errors when waiting for database in entrypoint

[matthewelwell]

Thanks for submitting a PR! Please check the boxes below:

• I have run pre-commit to check linting
• I have added information to docs/ if required so people know about the feature!
• I have filled in the "Changes" section below?
• I have filled in the "How did you test this code" section below?
• I have used a Conventional Commit title for this Pull Request

Changes

Based on a debugging session with a customer, it would be useful to be able to see the actual error message that occurs when waitfordb fails. This PR adds the relevant information as a secondary log message.

How did you test this code?

❯ DATABASE_URL=postgres://invalid-role:[email protected]:5432/flagsmith LOG_LEVEL=WARNING python manage.py waitfordb --waitfor 1
core.management.commands.waitfordb WARNING  Database not yet ready for connections.
core.management.commands.waitfordb WARNING  Error was: OperationalError: connection to server at "127.0.0.1", port 5432 failed: FATAL:  role "invalid-role" does not exist

core.management.commands.waitfordb WARNING  Database not yet ready for connections.
core.management.commands.waitfordb WARNING  Error was: OperationalError: connection to server at "127.0.0.1", port 5432 failed: FATAL:  role "invalid-role" does not exist

core.management.commands.waitfordb WARNING  Database not yet ready for connections.
core.management.commands.waitfordb WARNING  Error was: OperationalError: connection to server at "127.0.0.1", port 5432 failed: FATAL:  role "invalid-role" does not exist

core.management.commands.waitfordb WARNING  Database not yet ready for connections.
core.management.commands.waitfordb WARNING  Error was: OperationalError: connection to server at "127.0.0.1", port 5432 failed: FATAL:  role "invalid-role" does not exist

core.management.commands.waitfordb ERROR    Failed to connect to DB within 1 seconds.
Failed to connect to DB within 1 seconds.

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Apr 22, 2024 4:06pm
flagsmith-frontend-preview	✅ Ready (Inspect)	Visit Preview		Apr 22, 2024 4:06pm
flagsmith-frontend-staging	✅ Ready (Inspect)	Visit Preview		Apr 22, 2024 4:06pm

[github-actions]

Uffizzi Preview deployment-50605 was deleted.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 95.93%. Comparing base (7451032) to head (4f8c0a3).
Report is 5 commits behind head on main.

Files	Patch %	Lines
api/core/management/commands/waitfordb.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3823      +/-   ##
==========================================
- Coverage   95.93%   95.93%   -0.01%     
==========================================
  Files        1103     1103              
  Lines       34842    34843       +1     
==========================================
  Hits        33427    33427              
- Misses       1415     1416       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.