refactor ext db test into normal test matrix

[evgeni]

No description provided.

[evgeni]

@ehelms I didn't want to refactor it directly in #141, but I think this way it's nicer as it automatically benefits from any changes to our normal test workflow and the chances we forget something is smaller

[ehelms]

I wish the reporting was nicer to make it clear what was run:

[Test / tests (default, none, external) (pull_request)](https://github.com/theforeman/foremanctl/actions/runs/19888492813/job/57001229184?pr=348)
Test / tests (default, none, external) (pull_request)Successful in 34m
[Test / tests (default, none, internal) (pull_request)](https://github.com/theforeman/foremanctl/actions/runs/19888492813/job/57001229129?pr=348)
Test / tests (default, none, internal) (pull_request)Successful in 29m
[Test / tests (installer, none, internal) (pull_request)](https://github.com/theforeman/foremanctl/actions/runs/19888492813/job/57001229139?pr=348)
Test / tests (installer, none, internal) (pull_request)Successful in 31m

default, none, internal -- isn't the easy to understand at a glance that it's (certificates, security, database)

[evgeni]

Like this?

[evgeni]

I'll assume so :)

[ehelms]

Much better! Thanks!