Run Sonar report after fast checks

[ArBridgeman]

Summary

To aid developers, we want to run the Sonar report for these cases:

1. Immediately after the fast checks
2. After the slow checks

After 1. allows developers to more quickly get feedback on results (linting, security, unit tests) before running the slow tests, which sometimes have expensive or long delays. After 2. ensure that the coverage goals are met across the code itself.

To Do

• Update workflow templates merge-gate.yml
• Update PTB's merge-gate.yml file with nox -s workflow:generate --all
• Update the documentation:
  • https://exasol.github.io/python-toolbox/main/user_guide/features/github_workflows/index.html
• Update changelog & add to summary