Remove unnecessary recovery-related targets

Recovery should always use monolithic policy. Thus, we don't need
split policy files *.recovery.cil. This commit removes these targets
and rolls up the relevant parts of the targets into
"sepolicy.recovery" which is the target which produces monolithic
policy for recovery.

Test: make clean && make sepolicy.recovery, then confirm that
      repolicy.recovery is identical to the one produced prior to this
      change.
Test: Clean build, flash, device boots up fine, no new denials. Device
      also boots into recovery just fine, no denials.
Bug: 31363362

Change-Id: I7f698abe1f17308f2f03f5ed1b727a8b071e94c7