move MediaCodec metrics processing to looper thread

consolidate to avoid concurrency/mutex problems.

Bug: 256087846
Bug: 245860753
Test: atest CtsMediaV2TestCases
Test: atest CtsMediaCodecTestCases
Merged-In: Ie77f0028cab8091edd97d3a60ad4c80da3092cfe
Merged-In: I56eceb6b12ce14348d3f9f2944968e70c6086aa8
Merged-In: I94b0a2ac029dc0b90a93e9ed844768e9da5259b9
Change-Id: I739248436a4801a4b9a96395f481640f2956cedf