webrtc: use correct cwd for running tests

scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_linux_baremetal.json

Index: scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_linux_baremetal.json
diff --git a/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_linux_baremetal.json b/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_linux_baremetal.json
index ea93fa92aed79f631ad9f4a018614daaf2195e62..0fdceea1f911ef9bab280a750c8470370ec2d4f0 100644
--- a/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_linux_baremetal.json
+++ b/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_linux_baremetal.json
@@ -245,6 +245,7 @@
       "-u",
       "RECIPE_MODULE[build::webrtc]/resources/ensure_webcam_is_running.py"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_baremetal",
     "name": "webcam_check"
   },
   {
@@ -276,6 +277,7 @@
       "-pb",
       "[BUILDER_CACHE]/linux_baremetal/src/resources/audioproc.aecdump"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_baremetal",
     "name": "audioproc"
   },
   {
@@ -303,6 +305,7 @@
       "[BUILDER_CACHE]/linux_baremetal/src/resources/speech_and_misc_wb.pcm",
       "isac_speech_and_misc_wb.pcm"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_baremetal",
     "name": "isac_fix_test"
   },
   {
@@ -328,6 +331,7 @@
       "voe_auto_test",
       "--automated"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_baremetal",
     "name": "voe_auto_test"
   },
   {
@@ -352,6 +356,7 @@
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "video_capture_tests"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_baremetal",
     "name": "video_capture_tests"
   },
   {