Remove temp testing workflow & route on-demand workflow to selfhosted runner

[rzats]

Summary:

• Removes the one-time "performance testing testing" workflow from Performance testing testing workflow #1253.
• Modifies the performance testing workflow to route it to our self-hosted test runner, gh-runner-prod-cc-prv-01.

Prerequisites:

• Unless it is a documentation hotfix it should be merged against the dev branch
• Branch is up-to-date with the branch to be merged with, i.e. dev
• Build is successful
• Code is cleaned up and formatted

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
No Duplication information

[korlaxxalrok]

Yep, looks good!

(This may not work quite as expected until we modify/remove the WireGuard setup, but if it can be left as is will "just work" then even better, so I guess we try and see what happens)