fix(dockerfiles): clean up dangling sockets on startup (#10468)

[locao]

FTI-4525

(cherry picked from commit a6fe370)

Summary

This change adds a clean-up step to remove all sockets that a previous Kong run may have left in $PREFIX directory.

Checklist

• The Pull Request has tests
• There's an entry in the CHANGELOG
• There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Full changelog

Dangling unix sockets have been a pain point in recent Kong versions and was dealt in traditional Kong in #9254, but the kong script is not called when starting Kong inside a container, so a similar change to dockerfiles/entrypoint.sh was added here.

Issue reference

FTI-4525

[chronolaw]

I create a typo fix PR(#10482) for the original PR.

[bungle]

@locao should we squash and merge? If not then we need to fix the commits to proper format.

[locao]

@bungle I'll squash them, thanks!

[hbagdi]

Does this require any special handling in the EE codebase?

[locao]

Yes, I cherry-picked in Kong/kong-ee#4803.