chore: cleanup dead code for unsupported node versions

[blumamir]

This PR clean up some dead code related to node8 and node10 versions which is no longer supported

Minimum supported version for instrumentation is 14, as stated in package.json in each file

  "engines": {
    "node": ">=14"
  },

And there are no tests to verify any feature for older versions

[codecov]

Codecov Report

Merging #1391 (00b2088) into main (5a8df08) will increase coverage by 0.24%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1391      +/-   ##
==========================================
+ Coverage   96.10%   96.34%   +0.24%     
==========================================
  Files          14       20       +6     
  Lines         898     1123     +225     
  Branches      192      218      +26     
==========================================
+ Hits          863     1082     +219     
- Misses         35       41       +6     

Impacted Files	Coverage Δ
...ry-instrumentation-dns/src/enums/AttributeNames.ts	100.00% <ø> (ø)
...resource-detector-gcp/src/detectors/GcpDetector.ts	96.00% <100.00%> (ø)
...lemetry-instrumentation-dns/src/instrumentation.ts	95.65% <100.00%> (ø)
...ode/opentelemetry-instrumentation-dns/src/utils.ts	100.00% <100.00%> (ø)
...metry-resource-detector-gcp/src/detectors/index.ts	100.00% <0.00%> (ø)
...tapackages/auto-instrumentations-node/src/utils.ts	98.21% <0.00%> (ø)