Alerting: Log alert warnings for obsolete notifiers when extracting alerts and remove spammy error (#28162)

* Lower level of notification translation messages

* API: Log alert warnings when saving dashboard

* Remove spammy error

* Rename function parameter

* Apply suggestions from code review

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>

* Apply suggestions from code review

* Fix test

* Change alertValidator return type

* Small fix

* Rename symbol

* Revert "Rename symbol"

This reverts commit 40b619b21a336a8f635daf7ef4241e44a03f0977.

* Revert "Small fix"

This reverts commit 2df8319d1d0e8b9e4a3d18b36711e3ff53e6fa81.

* Revert "Change alertValidator return type"

This reverts commit ad933863e32057cf02caabaa5799e3c14033770d.

* Revert "Fix test"

This reverts commit f728ece2db9d45e7a78d31992082700b3fb4931d.

* Revert "Apply suggestions from code review"

This reverts commit f35c5f52af06a60cc39c8adf1508dce5a9a67052.

* Revert "Apply suggestions from code review"

This reverts commit 7f95800c5f0f1a7b552b7124f5dbeba349cce1d8.

* Revert "Rename function parameter"

This reverts commit 95d3e75b00c110e3e355ba069dbcd89939c2bee2.

* Revert "API: Log alert warnings when saving dashboard"

This reverts commit 1ac5c3f281263a2cad5d4136589ce1ece706752b.

* Conditionally log translation failures

* Fix issue causing test to fail

* Fix test

* Log instead of propagating translations failures due to database errors

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>