Fix cursor handling in ClusterEventService

[moesterheld]

Description

The ClusterEventService opened a cursor with TailableAwait, causing it to always stay in the cursor.hasNext() while loop in iterateEvents.
This replaces the loop condition with isRunning(). The tryNext() is sufficient as it will already null if no data is returned within maxAwaitTime. To make sure this is will not delay server shutdown maxAwaitTime is now set to 1s.

/nocl

Motivation and Context

fixes #25878

How Has This Been Tested?

adjusted unit tests

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have requested a documentation update.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.