Revert "ios: fix path to the test app"

scripts/slave/recipes/webrtc/ios.expected/infrastructure_failure.json

 [
   {
     "cmd": [
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/ios/host_info.py",
       "--json-file",
       "/path/to/tmp/json"
     ],
     "name": "host and tools info",
     "~followup_annotations": [
       "@@@STEP_TEXT@<br />OS X 1.2.3, Xcode 6.7.8 (5D342509a)@@@",
@@ skipping 173 matching lines @@
       "-C",
       "[BUILDER_CACHE]/ios/src/out/Debug-iphonesimulator"
     ],
     "cwd": "[BUILDER_CACHE]/ios/src/out/Debug-iphonesimulator",
     "name": "compile"
   },
   {
     "cmd": [
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/ios/run.py",
       "--app",
-      "[BUILDER_CACHE]/ios/src/out/Debug-iphonesimulator/fake tests 1.app",
+      "[SLAVE_BUILD]/src/out/Debug-iphonesimulator/fake tests 1.app",
       "--json_file",
       "/path/to/tmp/json",
       "--iossim",
-      "[BUILDER_CACHE]/ios/src/out/Debug-iphonesimulator/iossim",
+      "[SLAVE_BUILD]/src/out/Debug-iphonesimulator/iossim",
       "--platform",
       "fake device",
       "--version",
       "8.0"
     ],
     "name": "fake tests 1 (fake device iOS 8.0)",
     "~followup_annotations": [
       "step returned non-zero exit code: 2",
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"links\": {@@@",
@@ skipping 11 matching lines @@
       "@@@STEP_LOG_LINE@fake log@fake log line 2@@@",
       "@@@STEP_LOG_END@fake log@@@",
       "@@@STEP_LINK@fake URL text@fake URL@@@",
       "@@@STEP_EXCEPTION@@@"
     ]
   },
   {
     "cmd": [
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/ios/run.py",
       "--app",
-      "[BUILDER_CACHE]/ios/src/out/Debug-iphonesimulator/fake tests 2.app",
+      "[SLAVE_BUILD]/src/out/Debug-iphonesimulator/fake tests 2.app",
       "--json_file",
       "/path/to/tmp/json",
       "--iossim",
-      "[BUILDER_CACHE]/ios/src/out/Debug-iphonesimulator/iossim",
+      "[SLAVE_BUILD]/src/out/Debug-iphonesimulator/iossim",
       "--platform",
       "fake device",
       "--version",
       "7.1"
     ],
     "name": "fake tests 2 (fake device iOS 7.1)",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"links\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"fake URL text\": \"fake URL\"@@@",
@@ skipping 12 matching lines @@
       "@@@STEP_LINK@fake URL text@fake URL@@@"
     ]
   },
   {
     "name": "$result",
     "reason": "Failed fake tests 1 (fake device iOS 8.0).",
     "recipe_result": null,
     "status_code": 1
   }
 ]