meson: use gtest protocol for gtest based tests when possible
With the `gtest` protocol meson will add some extra arguments to the test to generate better junit results, which may be useful. This protocol is only available in meson 0.55.0+, so keep using the default `exitcode` protocol for meson older than that. Reviewed-by:Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com> Part-of: <!8484>