BUG/MINOR: stats: Add a break after filling ST_F_MODE field for servers

The previous patch was pushed too quickly (399bf72f6 "BUG/MINOR: stats:
Remove a break preventing ST_F_QCUR to be set for servers"). It was not an
extra break but a misplaced break statement. Thus, now a break statement
must be added after filling the ST_F_MODE field in stats_fill_sv_stats().

No backport needed except if the above commit is backported.
diff --git a/src/stats.c b/src/stats.c
index 1d5aa84..be8bc64 100644
--- a/src/stats.c
+++ b/src/stats.c
@@ -2069,6 +2069,7 @@
 				break;
 			case ST_F_MODE:
 				metric = mkf_str(FO_CONFIG|FS_SERVICE, proxy_mode_str(px->mode));
+				break;
 			case ST_F_QCUR:
 				metric = mkf_u32(0, sv->nbpend);
 				break;