radv: don't use a separate cache entry for GS copy shaders

radv: don't use a separate cache entry for GS copy shaders

This seems simpler and probably faster.

This also fixes a warning for these CTS tests:
dEQP-VK.pipeline.creation_feedback.graphics_tests.vertex_stage_geometry_stage_delayed_destroy_fragment_stage_delayed_destroy
dEQP-VK.pipeline.creation_feedback.graphics_tests.vertex_stage_geometry_stage_fragment_stage
because we no longer set found_in_application_cache=false for pipelines
with NGG GS.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13528>