webrtc: use correct cwd for running tests

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

Index: scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_linux_msan.json
diff --git a/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_linux_msan.json b/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_linux_msan.json
index ff07e6f42dfa1ba7f04e809d7b38472e13651eb8..5a93d9b614496a676e34348ddfaca13e664e94f3 100644
--- a/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_linux_msan.json
+++ b/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_linux_msan.json
@@ -285,6 +285,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/audio_decoder_unittests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "audio_decoder_unittests"
   },
   {
@@ -311,6 +312,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/common_audio_unittests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "common_audio_unittests"
   },
   {
@@ -337,6 +339,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/common_video_unittests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "common_video_unittests"
   },
   {
@@ -363,6 +366,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/modules_tests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "modules_tests"
   },
   {
@@ -389,6 +393,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/modules_unittests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "modules_unittests"
   },
   {
@@ -415,6 +420,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/peerconnection_unittests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "peerconnection_unittests"
   },
   {
@@ -441,6 +447,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/rtc_media_unittests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "rtc_media_unittests"
   },
   {
@@ -467,6 +474,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/rtc_pc_unittests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "rtc_pc_unittests"
   },
   {
@@ -493,6 +501,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/rtc_unittests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "rtc_unittests"
   },
   {
@@ -519,6 +528,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/system_wrappers_unittests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "system_wrappers_unittests"
   },
   {
@@ -545,6 +555,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/test_support_unittests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "test_support_unittests"
   },
   {
@@ -571,6 +582,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/tools_unittests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "tools_unittests"
   },
   {
@@ -597,6 +609,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/video_engine_tests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "video_engine_tests"
   },
   {
@@ -623,6 +636,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/voice_engine_unittests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "voice_engine_unittests"
   },
   {
@@ -649,6 +663,7 @@
       "[BUILDER_CACHE]/linux_msan/src/out/Release/xmllite_xmpp_unittests",
       "--"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "xmllite_xmpp_unittests"
   },
   {
@@ -674,6 +689,7 @@
       "--enable-msan",
       "webrtc_nonparallel_tests"
     ],
+    "cwd": "[BUILDER_CACHE]/linux_msan",
     "name": "webrtc_nonparallel_tests"
   },
   {