chromium_tests: pass paths to runit.py and runtest.py for src/testing/scripts

scripts/slave/recipes/android/perf.expected/provision_devices.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--master",
       "chromium.perf",
       "--builder",
       "Android Nexus5 Perf (1)",
@@ skipping 105 matching lines @@
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/src/testing/scripts/get_compile_targets.py",
       "--output",
       "/path/to/tmp/json",
       "--",
       "--build-config-fs",
       "Release",
       "--paths",
-      "{\"build\": \"[BUILD]\", \"checkout\": \"[SLAVE_BUILD]/src\"}",
+      "{\"build\": \"[BUILD]\", \"checkout\": \"[SLAVE_BUILD]/src\", \"runit.py\": \"RECIPE_PACKAGE_REPO[build]/scripts/tools/runit.py\", \"runtest.py\": \"RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py\"}",
       "--properties",
       "{\"buildername\": \"Android Nexus5 Perf (1)\", \"buildnumber\": 571, \"mastername\": \"chromium.perf\", \"perf-id\": \"android-nexus5\", \"results-url\": \"https://chromeperf.appspot.com\", \"slavename\": \"slavename\", \"target_platform\": \"android\"}"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "get compile targets for scripts",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{}@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
@@ skipping 216 matching lines @@
       "step returned non-zero exit code: 1",
       "@@@STEP_EXCEPTION@@@"
     ]
   },
   {
     "name": "$result",
     "reason": "Infra Failure: Step('provision_devices') returned 1",
     "status_code": 1
   }
 ]