Fix systemd unit override file permissions

Prod-Related: PROD-35976
Change-Id: I414adea650601f86b2f4e0993359368cd4522462
diff --git a/apache/server/service/init.sls b/apache/server/service/init.sls
index 6e6dab1..ce2e59b 100644
--- a/apache/server/service/init.sls
+++ b/apache/server/service/init.sls
@@ -121,6 +121,7 @@
   file.managed:
   - source: salt://apache/files/service.override.conf
   - template: jinja
+  - mode: 644
   - require:
     - file: /etc/systemd/system/apache2.service.d