Remove jack-related workaround

Remove comment and build instruction related
to a jack bug. These were introduced in commit 60370005.

Since we don't use Jack any more it should be
safe to remove.

Bug: 73644613
Test: make core-ojtests core-ojtests-public
Test: CTS: run cts -m CtsLibcoreOjTestCases
Change-Id: I5d998edc7c3ca52a4481bf45055a0ef00f4fc0b2