fix(docker-entrypoint): clean-up dangling unix sockets

[locao]

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

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

FTI-4525

[flrgh]

There's a nearly identical entrypoint script at ubuntu/docker-entrypoint.sh. Do these changes need to be added there as well?

[flrgh]

Mostly good to go! I requested a couple changes for bash quirks and some extra verbosity.

[Tieske]

There's a nearly identical entrypoint script at ubuntu/docker-entrypoint.sh. Do these changes need to be added there as well?

Yes, they should.

[locao]

There's a nearly identical entrypoint script at ubuntu/docker-entrypoint.sh. Do these changes need to be added there as well?

Good catch! Added the same set of changes to that file.