Fixes #34339 - sanitize fqdn in tests

Tests were almost not using the fqdn defined in settings.yaml.test
That is quite confusing at first sight and we should not override this value by fixtures, only if overriden in the same test file.

Fixes #31407 - prevent spaces for snapshot test files

Fixes #31370 - multi-host stub template snapshots (#8149)

Our snapshot template render test and generator only supports one host stub (ipv4 single NIC redhat OS). In order to test more ERB codepaths, we need a way to create snapshots against multiple host stubs (e.g. IPv6, dualstack, static IPv4 or IPv6, debian family). In order to do that, template metadata can be extended to define list of host stubs to create and test snapshots against....

Fixes #24294 - add snapshot tests for templates