Enabled coverage on mac builder

For more info : https://docs.google.com/document/d/1Q9oYW2w0-QTR6R8uI6yjriFu75e6_K50qcHyj3lda6c/edit

Bug: 1024915
Change-Id: I74e30d83b88361209259a1a63a477378ef86ef29
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2416062Reviewed-by: Garrett Beaty <gbeaty@chromium.org>
Reviewed-by: Erik Staab <estaab@chromium.org>
Commit-Queue: Prakhar Asthana <pasthana@google.com>
Auto-Submit: Prakhar Asthana <pasthana@google.com>
Cr-Commit-Position: refs/heads/master@{#808756}

infra/config/generated/cr-buildbucket.cfg

@@ -25249,7 +25249,7 @@ buckets {
         cipd_version: "refs/heads/master"
         cmd: "recipes"
       }
-      properties: "{\"$build/goma\":{\"jobs\":150,\"rpc_extra_params\":\"?prod\",\"server_host\":\"goma.chromium.org\",\"use_luci_auth\":true},\"$kitchen\":{\"devshell\":true,\"git_auth\":true},\"$recipe_engine/isolated\":{\"server\":\"https://isolateserver.appspot.com\"},\"builder_group\":\"tryserver.chromium.mac\",\"recipe\":\"chromium_trybot\"}"
+      properties: "{\"$build/code_coverage\":{\"use_clang_coverage\":true},\"$build/goma\":{\"jobs\":150,\"rpc_extra_params\":\"?prod\",\"server_host\":\"goma.chromium.org\",\"use_luci_auth\":true},\"$kitchen\":{\"devshell\":true,\"git_auth\":true},\"$recipe_engine/isolated\":{\"server\":\"https://isolateserver.appspot.com\"},\"builder_group\":\"tryserver.chromium.mac\",\"recipe\":\"chromium_trybot\"}"
       execution_timeout_secs: 14400
       expiration_secs: 7200
       caches {

infra/config/subprojects/chromium/try.star

@@ -1118,6 +1118,7 @@ try_.chromium_mac_builder(
 try_.chromium_mac_builder(
     name = "mac-rel",
     branch_selector = branches.STANDARD_RELEASES,
+    use_clang_coverage = True,
     goma_jobs = goma.jobs.J150,
     main_list_view = settings.main_list_view_name,
     os = os.MAC_DEFAULT,