Use the globals of the function when evaluating the return type for PlainSerializer and WrapSerializer functions

[Viicos]

Fixes #11004, follow up on #10929.

Change Summary

Related issue number

Checklist

• The pull request title is a good summary of the changes - it will be used in the changelog
• Unit tests for the changes exist
• Tests pass on CI
• Documentation reflects the changes where applicable
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

[cloudflare-workers-and-pages]

Deploying pydantic-docs with    Cloudflare Pages

Latest commit:	9b8caad
Status:	✅  Deploy successful!
Preview URL:	https://d6d377f4.pydantic-docs.pages.dev
Branch Preview URL:	https://func-rt-2.pydantic-docs.pages.dev

View logs

[codspeed-hq]

CodSpeed Performance Report

Merging #11008 will not alter performance

_{Comparing func-rt-2 (9b8caad) with main (8db4072)}

Summary

✅ 46 untouched benchmarks

[github-actions]

Coverage report

This PR does not seem to contain any modification to coverable code.

[sydney-runkle]

Good work, thanks for adding those descriptive comments.

Namespace stuff is so challenging.