[Update] Remove mailcow_anonymize_headers.pcre checks

[Postfix] Rename mailcow_anonymize_headers.pcre > anonymize_headers.pcre to prevent collisions

data/conf/postfix/anonymize_headers.pcre

@@ -0,0 +1,9 @@
+if /^\s*Received:.*Authenticated sender.*\(Postcow\)/
+/^\s*Received:.*Authenticated sender:(.+)/
+  REPLACE Received: from localhost (localhost [127.0.0.1]) (Authenticated sender:$1
+endif
+/^\s*User-Agent/        IGNORE
+/^\s*X-Enigmail/        IGNORE
+/^\s*X-Mailer/          IGNORE
+/^\s*X-Originating-IP/  IGNORE
+/^\s*X-Forward/         IGNORE