TT#72351 Restrict permissions for template to protect passwords

The templates does not really contain any passwords, but the file
generated from it will, so having the template have restricted
permissions means the generated one will inherit them.

Change-Id: I0ed38509e2c17eb4fd174722a0d01d31f4ef2816

debian/rules

@@ -12,3 +12,10 @@ override_dh_installdeb:
 	    rm -f "$$cf"; \
 	  fi; \
 	done
+
+D = debian/ngcp-system-tests
+
+override_dh_fixperms:
+	dh_fixperms
+	# The file generated from this template will contain passwords.
+	chmod 0600 $(D)/etc/ngcp-config/templates/etc/ngcp-system-tests/900_service-ngcp-api.yaml.tt2