chore: remove obsolete snapshots for webpack@4 and webpack-dev-server@3

[snitin315]

What kind of change does this PR introduce?
refactor.

Did you add tests for your changes?
No.

If relevant, did you update the documentation?
No.

Summary

Remove obsolete snapshots for webpack@4 and webpack-dev-server@3.

Does this PR introduce a breaking change?
No

Other information

I feel we should keep our snapshot resolver as it is because in the future we may want to support multiple versions like webpack 5 and webpack 6, dev-server v4, and dev-server v5 again.

webpack-cli/scripts/snapshotResolver.js

Lines 8 to 9 in 85bdd85

	const snapshotExtension = `.snap.webpack${webpackVersion}`;
	const snapshotExtensionForServe = `.snap.devServer${devServerVersion}.webpack${webpackVersion}`;

[codecov]

Codecov Report

Merging #3361 (961a1b0) into next (98a6fd0) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             next    #3361   +/-   ##
=======================================
  Coverage   93.07%   93.07%           
=======================================
  Files          22       22           
  Lines        1617     1617           
  Branches      457      457           
=======================================
  Hits         1505     1505           
  Misses        112      112           

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