fix(form-field): Displaying of mat-hint in combination with *ngIf

[dariobraun]

Fixes #9747 Closes #12859

[dariobraun]

@andrewseguin any feedback on this?

[dariobraun]

@andrewseguin is this still relevant?

[mmalerba]

@dariobraun I've rebased this for you and cleaned up some of the lint issues, but there's still failing tests on CI that will need to be fixed before this can go in

[mmalerba]

Closing since this fix is for the legacy mat-form-field which has been superseded by the MDC based one.

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