Extract shared request handler for GetXCom part

[xchwan]

related: #65570
@ferruzzi
For your plan
Phase 1: High-overlap handlers (three or more supervisors share this logic)
GetXCom - Activity, Triggerer, DFP
PutVariable - Activity, Triggerer, DFP
DeleteVariable - Activity, Triggerer, DFP
GetTICount - Activity, Triggerer, DFP
GetTaskStates - Activity, Triggerer, DFP
GetPreviousTI - Activity, Triggerer, DFP

I modify GetXCom part. I think split to each part can be easy for review/test/troubleshoot

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Was generative AI tooling used to co-author this PR?

• Yes (claude code Sonnet 4.6)

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[ferruzzi]

I think this is already handled in #65624 unless I am missing something?

[xchwan]

I’m aware of that PR, but I’m not sure whether it might be too large for other reviewers to spend time going through it thoroughly. Looking at the discussion, I haven’t seen much participation from reviewers besides you, so I tried splitting out one smaller part of the changes to see if it would be easier to get merged.

If this approach works, it might be a good way to gradually move the issue forward.

[ferruzzi]

That one has merged, if this is just a duplicate, then close it.

[ferruzzi]

blocking accidental merge

[xchwan]

I saw it merged, i'll close it.