revert: add node v18

[snitin315]

• This is a bugfix
• This is a feature
• This is a code refactor
• This is a test update
• This is a docs update
• This is a metadata update

For Bugs and Features; did you add new tests?

Motivation / Use-Case

I accidently pushed the last commit directly to master instead of another branch for adding node v18 on CI.

I am reverting it since the job seems to be taking longer than usual https://github.com/webpack/webpack-dev-server/runs/6144123429?check_suite_focus=true

Breaking Changes

None

Additional Info

No

[codecov]

Codecov Report

Merging #4402 (9aadb40) into master (54d4a94) will increase coverage by 0.12%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4402      +/-   ##
==========================================
+ Coverage   92.29%   92.42%   +0.12%     
==========================================
  Files          16       16              
  Lines        1597     1597              
  Branches      598      598              
==========================================
+ Hits         1474     1476       +2     
+ Misses        114      112       -2     
  Partials        9        9              

Impacted Files	Coverage Δ
lib/servers/WebsocketServer.js	94.87% <0.00%> (+5.12%)	⬆️

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