Fix NoSuchElementException in SessionCacheConfigTestServlet.testMXBeansEnabled

[riyaaroraa]

Defect #305111

This PR addresses the NoSuchElementException that was occurring in the SessionCacheConfigTestServlet.testMXBeansEnabled method. The issue was that the code was directly calling .next() on iterators without checking if they had elements, which could lead to NoSuchElementException when no MBeans were found.

The fix involves:

1. Storing the query results in a Set variable
2. Checking if the set is empty before attempting to get the next element
3. Throwing a more descriptive exception if no MBeans are found

[riyaaroraa]

!build (view Open Liberty Personal Build - ✅ completed successfully!)

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[LibbyBot]

Code analysis and actions

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[zhang-ca]

Looks good.