Attempt to fix podman DNS issue

[geoand]

As found by @holly-cummins, podman's internal DNS
is case-sensitive. This seems to be causing issues
for some our dev-services being run on podman.
This changes ensures that the hostname is always lowercase
thus circumventing the problem.

See this for a complete discussion

[holly-cummins]

I confirm this fixes the Mongo test cases in quarkus-integration-test-container-image-invoker, and so is a partial resolution of #25230. More generally, I think this is a sensible change. DNS is supposed to be case insensitive, so using mixed case names gains nothing and exposes us to bugs.

(Some libraries, like Mongo, do their own toLowerCase() on hostnames and so we're better off beating them to it and `toLowerCase()-ing first so hostnames are consistent throughout.)

[geoand]

Thanks a lot of the confirmation and more importantly for identifying the root cause of the problem @holly-cummins!
This exercise was super useful, although I am not sure it was not fun for you...