TT#108003 Fix memory leak in cdr_update_entry()

The AUTO_CLEANUP_INIT() macro is already allocating a string for this
variable, which we were then overwriting and thus leaking.

Change-Id: If655c867c5666c6cff6311f01e617647375f6279
Warned-by: coverity

daemon/cdr.c

@@ -49,8 +49,6 @@ void cdr_update_entry(struct call* c) {
 	if (!IS_OWN_CALL(c))
 		return;
 
-	cdr = g_string_new("");
-
 	/* CDRs and statistics */
 	if (_log_facility_cdr) {
 		g_string_append_printf(cdr, "ci=%s, ",c->callid.s);