Make android.os.BugreportParams.BUGREPORT_MODE_MAX_VALUE flagged

Although BUGREPORT_MODE_MAX_VALUE is a constant @TestApi, it should
not be exempted to be flagged. This is necessary to properly
generate SDK.

There is no change needed in caller side (the CTS BugreportManagerTest) because the flag protect the constant value which is the same no matter the flag is on or off.

Bug: 305067125
Test: atest BugreportManagerTest
Change-Id: I00047c5579c23a072b4300561c975debea8fe200
3 files changed