fix(opentelemetry-instrumentation): access require via globalThis to avoid webpack analysis

[overbalance]

Which problem is this PR solving?

When bundling with webpack, direct references to require in _warnOnPreloadedModules() cause webpack to analyze them as dependency expressions, leading to warnings or errors in bundled environments.

Short description of the changes

• Access require via globalThis instead of directly, preventing webpack from treating it as a static dependency
• Add an early return guard when require.resolve or require.cache are unavailable

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Verified existing tests pass in the instrumentation package
• Confirmed webpack builds no longer emit warnings for this require usage (located in separate PR)

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.70%. Comparing base (356ddee) to head (a5cba39).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6481   +/-   ##
=======================================
  Coverage   95.70%   95.70%           
=======================================
  Files         364      364           
  Lines       11779    11779           
  Branches     2751     2751           
=======================================
  Hits        11273    11273           
  Misses        506      506           

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