binderRpcTest: remove unit_test false

Yes, this is long-running, but without this, we don't
have a way to run it. Since we have results caching
for unmodified binaries, this should not cause a global
presubmit regression.

Bug: 416538918
Test: N/A
Change-Id: I8914f13181214403cbfe2a4bd3693970d5d6ac01