test_ec: Increase 'sleep_time' when waiting for queries

This should prevent/reduce tests' flakes.

CMK-22451

Change-Id: Ib0a49ae0b6f9f7280a4103555bd56dd47be9fee2
(cherry picked from commit c5d51d9)

Author: MatteoStifano

tests/integration/cmk/ec/test_ec.py

@@ -147,7 +147,7 @@ def _generate_message_via_syslog(
 def _wait_for_queried_column(
     site: Site,
     query: str,
-    sleep_time: float = 1,
+    sleep_time: float = 2,
     max_count: int = 20,
     strict: bool = True,
 ) -> list[str]: