[3.13] Fix unused value warnings and clean up unused map() in standard library modules (GH - 157053)

[evdakim1234]

Fixes #157053

Replaced unused variables with _ in Lib/_markupbase.py, Lib/idlelib/multicall.py, Lib/turtle.py to address static analysis warnings.
Remove redundant map() call in Lib/idlelib/searchengine.py

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[terryjreedy]

I think this should be closed because

1. The proposed changes, using _ instead of a name for unused loop variables and destructuring targets, is extremely nitpicky. Some of these have been present for over 20 years and have been ignored in previous unused name scans. I think at least some current idlelib code is better as is and I would reject the change.
2. The PR author has obviously not read the devguide.
   a. The PR targets 3.13 instead of main (now 3.16).
   b. The title does not include the issue number.
   c. After 3 hours, the PR author has not yet signed the CLA or other wise posted anything.
   Further review effort may be useless.

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[gvanrossum]

Agreed that the issue (#157053) and the PR should be closed on account of being just code churn, not in any way improvements.