Removing support for Azure AD Pod Identity authentication from KEDA on v2.15

[JorTurFer]

Proposal

AAD-Pod-Identity has gone out of support and it doesn't make sense to maintain that integration if MSFT doesn't do it.

The depreciation message is added by this PR and we should remove the feature from KEDA v2.15

Use-Case

No response

Is this a feature you are interested in implementing yourself?

No

Anything else?

No response

[zroubalik]

I agree.

[tomkerkhove]

Fine by me, but let's make sure we do everything according to https://github.com/kedacore/governance/blob/main/DEPRECATIONS.md#introducing-new-deprecations