PMM-8877: turn ON IA by default, mark fields as deprecated

[oter]

https://jira.percona.com/browse/PMM-8877

managed PR: https://github.com/percona/pmm-managed/pull/834 FB: https://github.com/Percona-Lab/pmm-submodules/pull/2043

[rnovikovP]

⚠️ Need to be merged when we are ready to GA Alerting

[it-percona-cla]

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2 out of 3 committers have signed the CLA.

:white_check_mark: oter
:white_check_mark: artemgavrilov
:x: Maksym Hilliaka

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