feat: set up mutt with isync

GitOrigin-RevId: ed8952fc9d50e6268991c6082bf99bc6db4bf247
diff --git a/.copybara/copy.bara.sky b/.copybara/copy.bara.sky
index 28ce726..1b049de 100644
--- a/.copybara/copy.bara.sky
+++ b/.copybara/copy.bara.sky
@@ -56,21 +56,14 @@
         after="dotfiles-external",
         paths = allPathsExceptCopybara,
       ),
-      core.transform(
-        transformations = [
-          core.replace(
-            before = "${internalCode}",
-            after = "",
-            multiline = True,
-            regex_groups = {
-              "internalCode": "(?m)^.*BEGIN-INTERNAL[\\w\\W]*?END-INTERNAL.*$\\n",
-            },
-            paths = allPathsExceptCopybara,
-          ),
-        ],
-        reversal = [],
-        # TODO: Remove this once some code uses this transformation.
-        noop_behavior = 'IGNORE_NOOP',
+      core.replace(
+        before = "${internalCode}",
+        after = "",
+        multiline = True,
+        regex_groups = {
+          "internalCode": "(?m)^.*BEGIN-INTERNAL[\\w\\W]*?END-INTERNAL.*$\\n",
+        },
+        paths = allPathsExceptCopybara,
       ),
       metadata.remove_label('Change-Id'),
     ],