Mute KqpStats.SysViewClientLost (#8301)

Author: naspirato

.github/config/muted_ya.txt

@@ -101,3 +101,4 @@ ydb/tests/functional/tenants test_storage_config.py.TestStorageConfig.*
 ydb/tests/functional/tenants test_tenants.py.*
 ydb/tests/functional/ydb_cli test_ydb_impex.py.TestImpex.test_big_dataset*
 ydb/tests/tools/pq_read/test test_timeout.py.TestTimeout.test_timeout
+ydb/core/kqp/ut/query KqpStats.SysViewClientLost