fix(internal/librarian/nodejs): remove Format step

[julieqiu]

The old OwlBot pipeline never ran eslint on generated code. Removes Format to match the existing pipeline behavior and avoid diffs during migration.

For #4743

[gemini-code-assist]

Code Review

This pull request removes the Format step from the Node.js library generation process. The changes involve removing the call to nodejs.Format in internal/librarian/generate.go, deleting the Format function itself from internal/librarian/nodejs/generate.go, and removing the corresponding tests and unused imports from internal/librarian/nodejs/generate_test.go. These changes are consistent with the goal of aligning the pipeline with the old OwlBot behavior, which did not run eslint on generated code. The code removal is clean and self-contained.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.25%. Comparing base (755c74d) to head (d7f88c7).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4792   +/-   ##
=======================================
  Coverage   81.25%   81.25%           
=======================================
  Files         129      129           
  Lines       10891    10875   -16     
=======================================
- Hits         8849     8836   -13     
+ Misses       1399     1396    -3     
  Partials      643      643           

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[jameslynnwu]

Should we create a task to https://github.com/googleapis/librarian/milestone/94 to add formatting back to nodejs generation?