[roll] Roll fuchsia Revert "[audio_core] Finalize new ReadLock semantics"

This reverts commit a8579d5c2d8b6544825df2a95241865938195dcd.

Reason for revert: http://fxb/95042 causing flakes in audio-policy-pipeline-test

Original change's description:
> [audio_core] Finalize new ReadLock semantics
>
> fxr/639969 defined new semantics for ReadLock. This CL enforces those
> semantics across audio_core. stream.h has been overwritten with
> stream2.h.
>
> The major changes are:
>
> 1. Subclasses now implement ReadLockImpl and TrimImpl instead of
>    ReadLock and Trim. This results in a bunch of small mechanical
>    changes across the code base.
>
> 2. EffectsStageV{1,2} are updated to meet the new semantics, including
>    ring out. Additionally, a number of bugs have been fixed (these bugs
>    were labeled TODOs in the old code). The two classes have essentially
>    identical implementations of ReadLockImpl and TrimImpl.
>
> 3. PacketQueue is updated to meet the new semantics. The old
>    implementation always returned the first packet in the queue, while
>    the new implementation intersects the first packet with the requested
>    range. Additionally, the new semantics make it easy to detect packet
>    underflows in PacketQueue -- this no longer happens in MixStage.
>
> 4. MixStage is updated to meet the new semantics, including ring out.
>    The old implementation had a lot of code to handle cases where the
>    source buffer was entirely in the past or entirely in the future.
>    Most of that code is obsolete with the new semantics, e.g., ReadLock
>    never returns a buffer "in the past". Since we can delete a lot of
>    code, I refactored MixStage::Mix to be (hopefully) simpler.
>
> This is a large CL. It's difficult to split this CL into smaller pieces
> without creating a temporary audio_core2 directory, which felt like
> overkill. To simpify the review, note that:
>
> - The review can be logically split into the four parts listed above
>   (EffectsStage, PacketQueue, MixStage, and everything else). You can
>   read and comment on one part at a time as if they are different CLs.
>
> - Since EffectsStageV{1,2} have essentially the same ReadLock code, I
>   suggest reviewing EffectsStageV1 carefully, then skim EffectsStage2.
>
> - stream2.h was moved into stream.h and the tempoary "::stream2"
>   namespace was removed. The diff looks large than reality because
>   Git/gerrit is unfortunately unable to recognize the file move.
>
> Other minor changes:
>
> - audio-capture-timestamp-validator was updated to use a shorter
>   impulse. Before this CL, the production effects added a long ramp-in
>   phase to each impulse, so to locate an impulse's leading edge, the
>   impulse needed to be wider than the ramp in (we used 35 frames).
>   After this CL, impulses have a short ramp-in phase. Wide impulses are
>   transformed to a short ramp in followed by a wave, and our existing
>   impulse detector is confused by this wave. To avoid this problem,
>   we've narrowed the impulse to 10 frames.
>
>   Note that this change to the production effects is WAI: this CL
>   actually fixes some long-standing bugs in effects handling. The
>   production effects should be more correct after this CL than before.
>
> Multiply: audio-core-fidelity-test
> Multiply: audio-renderer-pipeline-tests
> Multiply: audio-capturer-pipeline-tests
> Multiply: audio-policy-pipeline-tests
> Multiply: audio-clock-pipeline-tests
> Original-Fixed: 50669
> Original-Fixed: 73306
> Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/478521

No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/654309
Original-Revision: 39dcd1598803022ab157207c66ba474c94453d59
GitOrigin-RevId: f9f040e19e92ef0624fb09e23a2221ef00fe660e
Change-Id: I79f0360d04167846d126fab7f9f6be2293f525be