Cherry pick policy for third party only change

[powerivq]

We encountered a scenario where a third party only change was requested to be cherry picked into AMP stable bundle (https://github.com/ampproject/amphtml/issues/37485) .It does not appear to follow the existing cherry pick policy due to its impact on amp core is minimal since it only affects that certain vendor.

Due to the fact that verifying such a vendor-specific change was not a lot of work as the core was unchanged. Should we adjust our cherry pick policy (https://github.com/ampproject/amphtml/blob/main/docs/contributing-code.md#cherry-picks) by allowing such changes to be cherry picked if it causes significant breakages for that vendor? We may say P0 on a vendor is also CP-eligible.