Switch android.test and junit classes to use UnsupportedAppUsage

The UnsupportedAppUsage annotations could not be added directly to the
java files in src/ as they have to be built against the current api
which does not include the annotation. Instead this uses the same
technique as used for libcore/ojluni files and adds the annotations to
stub files (in hiddenapi/src) which are built as part of the
android.test.base-hiddenapi target. That target is added to a special
whitelist in build/soong/java/config/config.go which causes the
hiddenapi information to be extracted from the target.

Also, updates the preupload check to prevent anymore entries being
added to the config/hiddenapi-greylist.txt for android.test or junit
classes.

Bug: 73711752
Test: m cts-hiddenapi_flags-csv and check that it contained the
        correct entries even though they had been removed from
	config/hiddenapi-greylist.txt
Change-Id: Ifaf15d2751f54cb03f8402b866a0ee4da7acc4d2