Bug 1400181 - Return mochitests to structured logging; r=ahal

Removal of jetpack in bug 1371065 accidentally switched all remaining
mochitest flavors to unstructured; let's switch it back.

testing/mozharness/configs/unittests/linux_unittest.py

@@ -294,8 +294,7 @@ config = {
     "default_blob_upload_servers": [
         "https://blobupload.elasticbeanstalk.com",
     ],
-    "unstructured_flavors": {"mochitest": [],
-                            "xpcshell": [],
+    "unstructured_flavors": {"xpcshell": [],
                             "gtest": [],
                             "mozmill": [],
                             "cppunittest": [],

testing/mozharness/configs/unittests/mac_unittest.py

@@ -241,8 +241,7 @@ config = {
     "default_blob_upload_servers": [
         "https://blobupload.elasticbeanstalk.com",
     ],
-    "unstructured_flavors": {"mochitest": [],
-                            "xpcshell": [],
+    "unstructured_flavors": {"xpcshell": [],
                             "gtest": [],
                             "mozmill": [],
                             "cppunittest": [],

testing/mozharness/configs/unittests/win_unittest.py

@@ -264,8 +264,7 @@ config = {
     "default_blob_upload_servers": [
         "https://blobupload.elasticbeanstalk.com",
     ],
-    "unstructured_flavors": {"mochitest": [],
-                            "xpcshell": [],
+    "unstructured_flavors": {"xpcshell": [],
                             "gtest": [],
                             "mozmill": [],
                             "cppunittest": [],