feat: Add support to use pod identities for authentication in Azure Key Vault

[JorTurFer]

Signed-off-by: Jorge Turrado jorge_turrado@hotmail.es

This PR adds explicit support to use podIdentity only for Azure Key Vault and not for all scaler related things

Checklist

• Commits are signed with Developer Certificate of Origin (DCO - learn more)
• Tests have been added
• A PR is opened to update the documentation on (repo) feat: explain how to use pod identity for Azure Key Vault keda-docs#970
• Changelog has been updated and is aligned with our changelog requirements

Fixes #3813

[JorTurFer]

/run-e2e keyvault*
Update: You can check the progress here

[JorTurFer]

/run-e2e keyvault*
Update: You can check the progress here

[JorTurFer]

/run-e2e keyvault*
Update: You can check the progress here

[v-shenoy]

Besides the changes in 2.9 docs for adding this feature, we would require some changes in the earlier docs (I think 2.7, 2.8) to report this problem, right?

[JorTurFer]

Besides the changes in 2.9 docs for adding this feature, we would require some changes in the earlier docs (I think 2.7, 2.8) to report this problem, right?

I wouldn't change them, the feature it isn't documented in those version, so officially it doesn't exist xD

[v-shenoy]

I enabled pod identity / workload identity for key vault in #2907.
And I added to the docs as well in kedacore/keda-docs#752.

But now that I look at it, the page for keyvault still mentions that pod identity is not supported. Funny.

[JorTurFer]

But now that I look at it, the page for keyvault still mentions that pod identity is not supported. Funny.

That's why I said that it isn't documented xD
Maybe it was an error adding the files to the stage... I'll document this as part of v2.9, and I guess we don't need to update previous versions to explain it

[JorTurFer]

/run-e2e keyvault*
Update: You can check the progress here

[JorTurFer]

/run-e2e keyvault*
Update: You can check the progress here