Generate `//net/android:net_tests_java`

* This is crucial for net native unittests.
* Add public modifier to match the method definition. This was changed in aosp/2510260 because we run MTS tests against bootclasspath version. This can't be reverted until we stop jar-jaring the MTS tests.

Bug: 304215727
Bug: 304217500
Change-Id: I32e0ac1ebe6b82b76bd6d5179c6dc6e2926f96db
3 files changed