MDEV-26340: rsync uses `--whole-file` only in wan mode

This commit fixes a mistake where the --whole-file option
is used by rsync SST in WAN mode instead of LAN.

scripts/wsrep_sst_rsync.sh

@@ -388,7 +388,7 @@ EOF
         # Use deltaxfer only for WAN
         inv=$(basename "$0")
         WHOLE_FILE_OPT=""
-        if [ "${inv%wsrep_sst_rsync_wan*}" != "$inv" ]; then
+        if [ "${inv%wsrep_sst_rsync_wan*}" = "$inv" ]; then
             WHOLE_FILE_OPT="--whole-file"
         fi