Remove remaining TODOs from com.ibm.ws.messaging.comms.client

[volosied]

• I have considered the risk of behavior change or other zero migration impact (https://github.com/OpenLiberty/open-liberty/wiki/Behavior-Changes).
• If this PR fixes an Issue, the description includes "Fixes #FILLMEIN" or "Resolves #FILLMEIN" (verify release bug label if applicable: https://github.com/OpenLiberty/open-liberty/wiki/Open-Liberty-Conventions).
• If this PR resolves an external Known Issue (including APARS), the description includes "Fixes #FILLMEIN" or "Resolves #FILLMEIN".

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fixes #25963

// TODO: Verify Dynamic updates with SSL on Netty

• Verified via keystore updates and saw the code path entered

// TODO: Verify if this is used. See https://github.com/OpenLiberty/open-liberty/issues/22692

• Not implemented and no known tests enter that code

// TODO: This needs to be verified and implemented is not. https://github.com/OpenLiberty/open-liberty/issues/24814

• The FrameworkState.isStopping() was removed.
• Explicit closure during shutdown is cleaner than relying on Netty to forcibly terminate connections.
• Testing was performed on com.ibm.ws.jbatch.jms.throttle_fat's testThrottlingJobs where the messageEngineServer was shutdown during active connections.
  • With the check included, I saw numerous Connection unexpectedly broken during read. errors logged.
  • With it removed, the connections were explicitly closed.

There are other TODOs but they are not Netty related.

I didn't much improvement for Optionals, so I left it alone.

[volosied]

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

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[volosied]

Beta: https://wasrtc.hursley.ibm.com:9443/jazz/web/projects/WS-CD#action=com.ibm.team.build.viewDefinition&id=_O-0QwJNFEeqCQ8SNCJxVyQ

In Progress as of March 5th

[LibbyBot]

Code analysis and actions

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• 4 product code files were changed.
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[isaacrivriv]

!build
(view Open Liberty Personal Build - ❌ completed with errors/failures.)
command=ant -f build-test.xml localrun -propertyfile ../../../buildandbucket.properties -DhaltOnFailure=false -Dglobal.jvm.args="-Dcom.ibm.ws.beta.edition=true" -lib ../ant_build/lib.antClasspath

Note: Target locations of links might be accessible only to IBM employees.

[LibbyBot]

Code analysis and actions

DO NOT DELETE THIS COMMENT.

• 4 product code files were changed.
• Please describe in a separate comment how you tested your changes.