Test: Pass sized 1 vector to IDnsResolver::getResolverInfo

Prior to aosp/2152596, DnsResolver would crash if size of
wait_for_pending_req_timeout_count is 0. This change ensures the
crash won't happen, although it's not expected to see that the
latest tests are run on devices with old DnsResolver installed.

Bug: 237767883
Test: ResolverTest.ResolverStats passed on a device with old
      version of DnsResolver installed
Change-Id: Ic9c5b57e7576407132efbd16e58ba25c7fef6467