Fix discrepancy between from text vs source android_test_frameworks_core_stubs_current

Just like all other android_*_stubs_current modules,
android_test_frameworks_core_stubs_current is added to classpath of the
javac compilation of its reverse dependencies, and its static libs is
dynamically switched between the ".from-source" suffixed from-source
stub compiling java_library module and the ".from-text" suffixed
from-text stub compiling java_api_library module.

Other than the origin of the stubs, the two modules are expected to
contain (mostly) identical APIs. However, the two static libs of
android_test_frameworks_core_stubs_current currently do not follow this
principle as the from-source java_library module does not add the
"private-stub-annotation-jar" as static lib, while the from-text
java_api_library does. This discrepancy lead to compilation error of the
reverse dependencies when defaulting build to from-text stub generation.

This change fixes the discrepancy between the two modules by removing
"private-stub-annotation-jar" from the static lib of the from-source
module and making the two modules behave more similarly.

Test: patch on internal main and run `m framework-location.stubs.test.from-source --build-from-text-stub`
Bug: 301522358
Change-Id: I821b7bb25a8f7ec7f9977a01ebdfbd5f1b25cf5e