Reland "RNN VAD: pitch search optimizations (part 2)"

This reverts commit e6a731fceae9503f6237d3ea287323aeac732ea6.

Reason for revert: bug in parent CL fixed

Original change's description:
> Revert "RNN VAD: pitch search optimizations (part 2)"
>
> This reverts commit 2f7d1c62e21e2f3786c0803c973d71b414726d8d.
>
> Reason for revert: bug in ancestor CL https://webrtc-review.googlesource.com/c/src/+/191320
>
> Original change's description:
> > RNN VAD: pitch search optimizations (part 2)
> >
> > This CL brings a large improvement to the VAD by precomputing the
> > energy for the sliding frame `y` in the pitch buffer instead of
> > computing them twice in two different places. The realtime factor
> > has improved by about +16x.
> >
> > There is room for additional improvement (TODOs added), but that will
> > be done in a follow up CL since the change won't be bit-exact and
> > careful testing is needed.
> >
> > Benchmarked as follows:
> > ```
> > out/release/modules_unittests \
> >   --gtest_filter=*RnnVadTest.DISABLED_RnnVadPerformance* \
> >   --gtest_also_run_disabled_tests --logs
> > ```
> >
> > Results:
> >
> >       | baseline             | this CL
> > ------+----------------------+------------------------
> > run 1 | 23.568 +/- 0.990788  | 22.8319 +/- 1.46554
> >       | 377.207x             | 389.367x
> > ------+----------------------+------------------------
> > run 2 | 23.3714 +/- 0.857523 | 22.4286 +/- 0.726449
> >       | 380.379x             | 396.369x
> > ------+----------------------+------------------------
> > run 2 | 23.709 +/- 1.04477   | 22.5688 +/- 0.831341
> >       | 374.963x             | 393.906x
> >
> > Bug: webrtc:10480
> > Change-Id: I599a4dda2bde16dc6c2f42cf89e96afbd4630311
> > Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/191484
> > Reviewed-by: Per Åhgren <peah@webrtc.org>
> > Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
> > Cr-Commit-Position: refs/heads/master@{#32571}
>
> TBR=alessiob@webrtc.org,peah@webrtc.org
>
> Change-Id: I53e478d8d58912c7a5fae4ad8a8d1342a9a48091
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: webrtc:10480
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/192620
> Reviewed-by: Alessio Bazzica <alessiob@webrtc.org>
> Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#32580}

TBR=alessiob@webrtc.org,peah@webrtc.org

# Not skipping CQ checks because this is a reland.

Bug: webrtc:10480
Change-Id: I0d6c89c64587bb6c38e69b968df12a5eb499ac6f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/192782
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Reviewed-by: Alessio Bazzica <alessiob@webrtc.org>
Reviewed-by: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32586}