types: remove legacy AbortSignal alias now provided by @types/node

[trivikr]

This relates to...

N/A

Rationale

This alias was originally added in #482 before @types/node exposed AbortSignal, but that is no longer necessary. Relying on the upstream type definition keeps the dispatcher typings simpler and avoids maintaining a redundant alias.

Changes

Remove the local AbortSignal alias from types/dispatcher.d.ts.

Features

N/A

Bug Fixes

N/A

Breaking Changes and Deprecations

N/A

Status

• I have read and agreed to the Developer's Certificate of Origin
• Tested
• Benchmarked (optional)
• Documented
• Review ready
• In review
• Merge ready

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.87%. Comparing base (51cc6cb) to head (c2320be).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4995   +/-   ##
=======================================
  Coverage   92.86%   92.87%           
=======================================
  Files         110      110           
  Lines       35788    35788           
=======================================
+ Hits        33236    33238    +2     
+ Misses       2552     2550    -2     

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[mcollina]

lgtm