net-test: remove forwarding_test

per Lorenzo this is no longer needed

Bug: 239416185
Test: N/A
Signed-off-by: Maciej Żenczykowski <maze@google.com>
(cherry picked from https://android-review.googlesource.com/q/commit:9a465b0b05dc04acb5907b72932a238d5a863312)
Merged-In: I7e8c1dacf3ec8b13805b6960bbce5a664c8d3648
Change-Id: I7e8c1dacf3ec8b13805b6960bbce5a664c8d3648