Correct URL handling for Elasticsearch/OpenSearch

[webbnh]

Now that we are deploying on an OpenSearch service which requires a username/password, remove assumptions around the contents of the ES URL configuration in the Server code.

• Remove the check for a port from wait_for_uri(); add defaulting for the port number if it is omitted.
• Rework _get_es_hosts() to return the whole URL instead of the decomposed dict; move the specification of the timeout value to its caller.
• Add a ca_bundle configuration option to the Indexing configuration section and pointed the default value for it to /etc/pki/tls/certs/ca-bundle.crt.
• Provide the ca_bundle value to the instantiations of the Elasticsearch client and to the Requests methods which target Elasticsearch/OpenSearch services.
• Remove the unused logger parameter from get_es() and _get_es_hosts().
• Clear some lint.

PBENCH-1302

[webbnh]

I find myself wondering about the implications if we install somewhere without a /etc/pki/tls/certs/ca-bundle.crt

In that case (or in any other case where the "trusted CAs" are in some other file), the installation will need to override the default ca_bundle value using the pbench-server.cfg file. (I don't think that this is particularly weird -- yeah, it would be nicer if the CA bundle location were standard, but, since it's not, I think this defaulting serves us well without being overly restrictive.)

it seems that the CI ran with straight http Elasticsearch so at least that's covered, and I assume this will also work for the staging server.

I concur.

I suppose we may find further problems when the Opensearch permissions are fixed (if that's really the problem), but for now this looks OK.

I'm hoping that the remaining blockers are all DevOps issues and not code (etc.) issues, but I'm inclined to hold off on merging this until we have confirmation of that. However, I've rebased on the end of main to pick up the logging changes.