The goal of query_info_hook_test is to ensure query_info_collect_hook
are placed in porper location for emitting query execution metrics.
This test was flaky due to uncertain order of calling between QD and
QEs when the interconnect in TCP mode.
This fix simply silent all QEs from emitting messages.
This is acceptable from the scope of this test because we just want
to make sure hooks are called at correct timing for each backend.
It should not be disturbed by query dispatching between QD and QEs.