suites: thrash old client missing SLOW_OPS in the ignore-list

The current ignore-list have \(SLOW_OPS\)  but missing SLOW_OPS

Fixes: https://tracker.ceph.com/issues/66604
Signed-off-by: Nitzan Mordechai <[email protected]>

Author: NitzanMordhai

qa/tasks/thrashosds-health.yaml

@@ -13,7 +13,7 @@ overrides:
       - \(CACHE_POOL_
       - \(SMALLER_PGP_NUM\)
       - \(OBJECT_
-      - \(SLOW_OPS\)
+      - SLOW_OPS
       - \(REQUEST_SLOW\)
       - \(TOO_FEW_PGS\)
       - slow request