pkg/machine: remove unused InstalledProviders function

[Aryanbhargava18]

Checklist

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What this PR does / why we need it:

The InstalledProviders function in pkg/machine/provider/platform.go is unused everywhere in the codebase except within its own test cases. This PR removes the dead code entirely to clean up the API surface.

Does this PR introduce a user-facing change?

None

[danishprakash]

Do we even need InstalledProviders, doesn't seem to be used afaict. cc/ @ashley-cui

[Aryanbhargava18]

Good catch @danishprakash. I audited the tree and InstalledProviders() isn't consumed anywhere outside of platform_test.go. I originally just patched the test to resolve the immediate CI flake on developer environments, but if it's dead code, deleting it entirely is definitely the cleaner fix.

I'm happy to push a commit to this PR dropping the function and its tests entirely if you and @ashley-cui agree.

[ashley-cui]

Looks like dead code to me, I'd be okay with removing it.

[packit-as-a-service]

[NON-BLOCKING] Packit jobs failed. @containers/packit-build please check. Everyone else, feel free to ignore.

[Aryanbhargava18]

I've dropped InstalledProviders() and its associated tests entirely in the latest commit as discussed. Ready for another look whenever you have time @danishprakash @ashley-cui.

[danishprakash]

There seems to be some issues, can you please run make validatepr and fix them?

[Aryanbhargava18]

There seems to be some issues, can you please run make validatepr and fix them?

Deleting the function left behind an unused import (define) in platform.go. I've dropped the unused import and ran gofmt in the latest push. It should be fine now.

[danishprakash]

do you mind also cleaning up SupportedProviders and associated tests? that's also dead

[Aryanbhargava18]

do you mind also cleaning up SupportedProviders and associated tests? that's also dead

Done. I went ahead and purged SupportedProviders and its associated tests across all architectures since they were dead code as well.