Revert "Change SetLocalContent / SetRemoteContent to update header extensions"

This reverts commit 9496cc0e1b8cc50185ded19522b68d7c94c17298.

Reason for revert: Investigating downstream issue.

Bug: webrtc:383078466
Original change's description:
> Change SetLocalContent / SetRemoteContent to update header extensions
>
> The functions were skipping over updating the sender and receiver when
> the list of header extensions was changed. Now it should be better.
>
> Bug: webrtc:383078466, b/425662432, b/426394283
> Change-Id: I1b93ed1ba4bbbf6c5b13861a6e21a7a7c82a5a66
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/396640
> Reviewed-by: Per Kjellander <perkj@webrtc.org>
> Commit-Queue: Harald Alvestrand <hta@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#44951}

Bug: webrtc:383078466
Change-Id: Ie6db6d995021a8699c1c7aa91334ea0ea0e37c1f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/397820
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Owners-Override: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Christoffer Dewerin <jansson@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#45012}