[#IOPID-2048] Add Service Temporary Unavailable middleware

[gquadrati]

List of Changes

• Add new middleware that returns 504 when server is under pressure (based on event loop metric)
• Trace metrics of event loop delay (mean and 95 percentile) every 5 seconds
• Add EVENT_LOOP_DELAY_THREASHOLD variabile, with default

Motivation and Context

Avoid server overload and minimize requests in timeout

How Has This Been Tested?

manual tests

Screenshots (if appropriate):

Types of changes

• Chore (nothing changes by a user perspective)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[github-actions]

Jira Pull Request Link

This Pull Request refers to the following Jira issue IOPID-2048

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
87.1% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud