Freezer: improve file lock exemption

When a process becomes cached and holds file locks blocking other
processes, check whether those blocked processes are also in cached
mode. If they are also cached, freeze the current process. Otherwise,
Skip the current process to avoid deadlock.

Bug: 245994713
Bug: 253913470
Test: atest ProcLocksReaderTest
Test: verify apps with deadlock can be frozen
Change-Id: I8635bf877bbe4404cc66955f1946444265680246