Remove enabled flag explicit_refresh_rate_hints

It has been enabled for a year.

Bug: 300019131
Test: TransitionTests#testTransitionsTriggerPerformanceHints
Flag: EXEMPT removing com.android.window.flags.explicit_refresh_rate_hints
Change-Id: I26b717c8ac6c53faef5d1a51b65ea490643a2146
8 files changed