feat: Add metrics about the SQLAlchemy database pool

[MoritzWeber0]

Adds the following to the /metrics endpoint:

# HELP sqlalchemy_pool_size SQLAlchemy database connection pool size
# TYPE sqlalchemy_pool_size gauge
sqlalchemy_pool_size 20.0
# HELP sqlalchemy_connections_in_pool Available database connections in the SQLAlchemy pool
# TYPE sqlalchemy_connections_in_pool gauge
sqlalchemy_connections_in_pool 1.0
# HELP sqlalchemy_pool_overflow Overflow of the SQLAlchemy database connection pool
# TYPE sqlalchemy_pool_overflow gauge
sqlalchemy_pool_overflow -19.0
# HELP sqlalchemy_checked_out_connections Checked out SQLAlchemy database connections
# TYPE sqlalchemy_checked_out_connections gauge
sqlalchemy_checked_out_connections 0.0

[codecov]

Codecov Report

Attention: Patch coverage is 89.74359% with 4 lines in your changes missing coverage. Please review.

Project coverage is 84.70%. Comparing base (ce5cb51) to head (c113366).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
backend/capellacollab/core/database/metrics.py	86.66%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1925      +/-   ##
==========================================
+ Coverage   84.68%   84.70%   +0.02%     
==========================================
  Files         206      208       +2     
  Lines        6739     6774      +35     
  Branches      463      463              
==========================================
+ Hits         5707     5738      +31     
- Misses        870      874       +4     
  Partials      162      162              

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[github-actions]

API Changelog 4.8.3.dev11+g97dc5282

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[github-actions]

This report was generated by comparing 97dc528 with ce5cb51.
If you would like to check difference, please check here.

ArtifactName: reg

✨✨ That's perfect, there is no visual difference! ✨✨

item	count
pass	342
change	0
new	0
delete	0