Allow Tuner to update client priority without override the default

priority

The updateResourcePriority(int, int) in Tuner used to update priority
and nice value at the same time.

Now we bypass the priority settings with only nice value setting
in the Tuner Resource Manager when the user gives negative priority.

Test: atest com.android.server.tv.tunerresourcemanager
Bug: 176186744
Change-Id: I0dc1326691ac02b4dc4d8f9c0252f6150284ef82