fix(api): re-introduce fallback chain for global utils

[pichlermarc]

Which problem is this PR solving?

This re-introduces the fallback chain that was removed in #6208, causing API incompatibility with Node.js v8.

Assisted-by: GitHub Copilot using Claude Sonnet 4.6

Fixes #6522

Short description of the changes

• added fallback chain for Node.js 8 compatibility, aims to keep the original intentions of refactor: consolidate platform-specific code #6208
  • we can follow-through with removing old browser support in 1.10.0, but for a bugfix release this change here should be more appropriate.
• Added backcompat smoke-tests for Node.js 8 (I'm very open for discussion on this, seems very tacked on but I think this is the only way to truly test this)

Type of change

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

How Has This Been Tested?

• manual testing using repro from [api] incompatible with Node.js 8 #6522
• ran added tests locally
• ran added tests in CI

[codecov]

Codecov Report

❌ Patch coverage is 22.22222% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.68%. Comparing base (b5a6b12) to head (8516a0e).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
api/src/internal/global-utils.ts	22.22%	7 Missing ⚠️

❌ Your patch status has failed because the patch coverage (22.22%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6523      +/-   ##
==========================================
- Coverage   95.73%   95.68%   -0.06%     
==========================================
  Files         364      364              
  Lines       12104    12112       +8     
  Branches     2887     2895       +8     
==========================================
+ Hits        11588    11589       +1     
- Misses        516      523       +7     

Files with missing lines	Coverage Δ
api/src/internal/global-utils.ts	82.05% <22.22%> (-17.95%)	⬇️

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[pichlermarc]

Note: failing coverage is expected since we don't generate coverage reports for it. this is intentional as we'd have to hold back coverage libraries to Node.js 8 compatibility which is not practical.