Revert "Reland "Notify first packet received after receptiveness change""

This reverts commit 0ef42fdc4b10969fe19ebfeaec326ec80b24fd4f.

Reason for revert: Breaks downstream project

Original change's description:
> Reland "Notify first packet received after receptiveness change"
>
> This is a reland of commit a14f6dc908f5e23c2b58062f5ae3bfbd7aec8502
>
>
> PS1: original change
> PS2..3: add default to Java observer
> PS4..5: use absl::AnyInvocable instead of std::function
>
> Original change's description:
> > Notify first packet received after receptiveness change
> >
> > similar to NotifyFirstPacket but fires after changes to
> > the receptiveness.
> >
> > No-IWYU: bot broken
> > Bug: chromium:40821064
> > Change-Id: I9fc9a229a13891dee2f286faadb8a53e54cd370d
> > Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/411380
> > Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> > Reviewed-by: Henrik Boström <hbos@webrtc.org>
> > Commit-Queue: Philipp Hancke <philipp.hancke@googlemail.com>
> > Cr-Commit-Position: refs/heads/main@{#46158}
>
>
> No-IWYU: bot broken
> Bug: chromium:40821064
> Change-Id: Ibf7cca9074a2657bb31915959afbfa0b3cc3d8c4
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/424880
> Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> Reviewed-by: Henrik Boström <hbos@webrtc.org>
> Commit-Queue: Philipp Hancke <philipp.hancke@googlemail.com>
> Cr-Commit-Position: refs/heads/main@{#46177}

Bug: chromium:40821064
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: Ib9c668bec730cd68ba901054c51997e1bf759a58
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/425442
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Auto-Submit: Fredrik Solenberg <solenberg@webrtc.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#46187}