fix: replace MDN contact email address (#3678)

`mdn@mozilla.com` does not actually exist.

dags.yaml

@@ -1001,7 +1001,7 @@ bqetl_mdn_yari:
     depends_on_past: false
     email:
       - telemetry-alerts@mozilla.com
-      - mdn@mozilla.com
+      - mdn-infra@mozilla.com
       - fmerz@mozilla.com
       - kignasiak@mozilla.com
     email_on_failure: true

dags/bqetl_mdn_yari.py

@@ -30,7 +30,7 @@ default_args = {
     "end_date": None,
     "email": [
         "telemetry-alerts@mozilla.com",
-        "mdn@mozilla.com",
+        "mdn-infra@mozilla.com",
         "fmerz@mozilla.com",
         "kignasiak@mozilla.com",
     ],
@@ -62,7 +62,7 @@ with DAG(
         email=[
             "fmerz@mozilla.com",
             "kignasiak@mozilla.com",
-            "mdn@mozilla.com",
+            "mdn-infra@mozilla.com",
             "telemetry-alerts@mozilla.com",
         ],
     )