Error fix from enabling Clang thread-safety checks

Parent bug: b/353324127. Enabling `thread-safety-reference-return`
to allow developers to utilize Clang thread safety guardrails
(GUARDED_BY, REQUIRES, EXCLUDES).

Added NO_THREAD_SAFETY_ANALYSIS annotations to violating functions.
If this is not desired, please respond with concerns
or preferred fix.

Bug: 354740314
Test: m  libsurfaceflinger_unittest
Change-Id: I590ab37c7abe727ab827a99d2917dd15b534e1cf