[Stats] Remove jitterBufferDelay TODO; it's already implemented.
[Stats] Remove jitterBufferDelay TODO; it's already implemented.

This TODO says this metric is only available for audio and should also
be implemented for video, but ever since M76 this has been implemented
for both audio and video (https://crbug.com/webrtc/10450).

TBR=guido@webrtc.org, hta@webrtc.org
NOTRY=True

Bug: webrtc:10450
Change-Id: Icf2b60fdacae606c66f9d03492f107df9e32ba33
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/168343
Reviewed-by: Henrik Boström <106ab6647ddadbf38d6259e9d5ec4de77fa52c00@webrtc.org>
Commit-Queue: Henrik Boström <106ab6647ddadbf38d6259e9d5ec4de77fa52c00@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#30485}

TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc