[WIP] v4l2-decoder: Remove media tree monitoring, add stable-rc_6.6

[denisyuji]

As per internal discussion (ref: https://issuetracker.google.com/issues/371638530 ), we will not monitor media branch for fluster/tast v4l2 decoder tests neither for ChromeOS or Debian rootfs. We will keep monitoring next branch for fluster tests for now and evaluate its value later. In addition, ChromeOS will stay in stable-rc_6.6 and eventually stable-rc_6.12, so we will keep monitoring this branch.

[nuclearcat]

AFAIK there is no such tree as stable-rc_6.6.
I added documentation for rules parameter: #899 if it will help.
stable-rc_6.6 is name of one of build configurations, it cannot be used in rules.

[laura-nao]

@denisyuji from my understanding, the codec tests are going to target the 6.6 LTS (and the 6.12 LTS later).

As far as I can see we're not tracking the 6.6 LTS tree/branch at the moment (that's different from stable-rc). In that case, I think we should start tracking the linux-6.6.y branch of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git . That can be done by adding the URL to the trees: section of the pipeline.yaml file, and then adding a stable_6.6 build configuration to track the linux-6.6.y branch (similar to what has been done for stable-rc).
I think that should be enough to start tracking the 6.6 LTS in KernelCI, right @nuclearcat ?

[nuclearcat]

Yes, here is example: #807