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

scripts/slave/recipes/chromium.expected/amp_split_recipe_collect_failure.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--master",
       "chromium.fyi",
       "--builder",
       "Android Tests (amp split)",
@@ skipping 118 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 Tests (amp split)\", \"buildnumber\": \"77457\", \"mastername\": \"chromium.fyi\", \"slavename\": \"build1-a1\", \"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 2195 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@  os.remove(report)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "name": "$result",
     "reason": "1 tests failed: ['base_unittests']",
     "status_code": 1
   }
 ]