fix(infra) add support for internal ACPs

[dduportal]

Related to https://github.com/jenkins-infra/helpdesk/issues/3954#issuecomment-2114950444

This PR is a medium-term fix to ensure the new "internal" (without public ingress) ACP (in the ci.jenkins.io-agents-1 AKS cluster) can be used without failing the healthcheck.

Notes:

• The configuration (provider names and URL) is already spread between the code here and the puppet templates. This is not the scope of this PR (hence the "middle term") patch.
• The condition is ready to support internal ACPs for future EKS or DOKS using the pattern (.*)ks-internal for the name

[dduportal]

Currently testing in https://github.com/jenkinsci/jenkins-infra-test-plugin/pull/126

[dduportal]

External test in https://github.com/jenkinsci/jenkins-infra-test-plugin/pull/126 worked as expected:

9:24:03  + curl --fail --silent --show-error --location http://artifact-caching-proxy.artifact-caching-proxy:8080/health
19:24:03  OK
19:24:04  INFO: using artifact caching proxy from 'azure-aks-internal' provider.

and tested with an existing one (to ensure no regression):

19:31:41  + curl --fail --silent --show-error --location https://repo.aws.jenkins.io/health
19:31:41  OK
19:31:41  INFO: using artifact caching proxy from 'aws' provider.

=> Self merging