Remove a couple of TODOs in BroadcastQueueModernImpl.

Legacy queue used to delay broadcasts in some cases
where no. of bg services are above a certain threshold.
Modern queue does not do this, so ignore a couple of
callbacks related to this behavior.

Bug: 261899716
Test: TH
Change-Id: Ifa3612ea2a0e9ced16407391ed532c5b8345583c