Removing tests/asyncqueue-test.c from tests/

Tests on async queues are already performed in a more extensive way in
glib/tests/asyncqueue.c. This test file can be safely removed without
any loss.

tests/meson.build

@@ -29,7 +29,6 @@ tests = {
   'mainloop-test' : {},
   'mapping-test' : {},
   'onceinit' : {},
-  'asyncqueue-test' : {},
   'relation-test' : {},
   'slice-concurrent' : {},
   'slice-threadinit' : {