prepareInitialInputBuffer : retry buffers

During flush, if all input buffers are still with component,
We retry to get buffers to proceed.

Bug: 291241758
Bug: 296988490

Test: atest android.media.decoder.cts.AdaptivePlaybackTest
Test: atest android.media.cts.MediaCodecTest
Test: atest android.mediav2.cts.CodecDecoderTest
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:ef235a9a63e1b20f7de24d900db5e834f24e1ddb)
Merged-In: I6326c4c8542844cf7edb4c22054cc16a596c0af2
Change-Id: I6326c4c8542844cf7edb4c22054cc16a596c0af2