Partially revert "[runtimes] Use add_lit_testsuite to register lit testsuites"

This partially reverts commit e1173c8794f4942d2cdddb090489ba5a6cc193e8
until we find out why libcxx tests are failing under runtimes build.

GitOrigin-RevId: f4059cc35267b365005a2002fe4182002401dda6
1 file changed