mavsdk_tests: adjust px4 and gzserver priority relative to mavsdk_test
mavsdk_tests: adjust px4 and gzserver priority relative to mavsdk_test

 - this is to avoid starving the test runner

krbeverx/Firmware,acfloria/Firmware,krbeverx/Firmware,acfloria/Firmware,krbeverx/Firmware,krbeverx/Firmware,acfloria/Firmware,acfloria/Firmware,krbeverx/Firmware,acfloria/Firmware,acfloria/Firmware,krbeverx/Firmware,krbeverx/Firmware,acfloria/Firmware