[VTS] Add more time for wpa_supplicant to stop

Failure in the bug may be related to the fact that the phone's
CPU was busy and supplicant daemon was not killed within 5 seconds.
This change increases the timeout to 20 seconds, similarly to the
wait time for starting the daemon.

Bug: 134090626
Test: vts-tradefed run commandAndExit vts --skip-all-system-status-check --primary-abi-only --skip-preconditions --module VtsHalWifiSupplicantV1_2Host
Change-Id: I02a577a8ecdd839a94a4a56a5ad9a7abe2d14e8f
1 file changed