Hide getDefaultTransactionName and getTransactionName

The two methods are now with @hide as they are not intended for public
use.

Bug: 124210145
Test: m
Test: aidl_unittests
Merged-In: I8665f11e8912159d37f0d54e643df25cdacf9e16
Change-Id: I8665f11e8912159d37f0d54e643df25cdacf9e16
2 files changed