Revert "Expose ServiceManager.waitForService as system API."

This reverts commit ee13e8d4.

Reason for revert: As discussed in b/233915142, an API that can obtain an arbitrary binder should not be exposed, and mainline modules should generally follow go/android-api-guidelines#the-moduleservicemanager-pattern.

Bug: 233915142
Test: Presubmit
Change-Id: I67e6e177d48ed213306aa0c10f83fe3b670daf1d