cameraservice: Allow AIDL Devices to not support sensor readout timestamp

CameraService currently force adds
ANDROID_SENSOR_READOUT_TIMESTAMP_HARDWARE to all AIDL devices. This
effectively means all Camera HALs implementing the AIDL interfaces
are forced to support sensor timestamp.

Forcing AIDL HALs to support sensor readout timestamp means HALs will
have to fake sensor readout value if the camera sensor does not report
sensor readout timestamp (for example in the case of ExternalCameraHAL).

This CL allows AIDL HALs to not support sensor readout timestamp.

Bug: 309543399
Test: ReadoutTimestampTest#testReadoutTimestamp passes for
      ExternalCameraHAL
Test: atest CtsCameraTestCases:android.hardware.camera2.cts.ReadoutTimestampTest
      passes for normal AIDL HALs when the value is not explicitly set.
Change-Id: Iecf84372f2f6e2812d9c148a94b15eed01917fb1