Delete requested_resolution, the old name for scale_resolution_down_to.

Now that Chromium and internal_compile_lite have migrated we can delete
the old name.

Bug: webrtc:375048799
Change-Id: I11d79f1d4ef1c0aa132cb50856faf83250e07caf
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/366600
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Auto-Submit: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43312}