[chore][puppet tests] Upgrade minimum Node.js version to v18

[crobert-1]

Description:

Failure link:

Notice: /Stage[main]/Splunk_otel_collector/Exec[Install splunk-otel-js]/returns: npm WARN EBADENGINE Unsupported engine {
Notice: /Stage[main]/Splunk_otel_collector/Exec[Install splunk-otel-js]/returns: npm WARN EBADENGINE   package: '@splunk/[email protected]',
Notice: /Stage[main]/Splunk_otel_collector/Exec[Install splunk-otel-js]/returns: npm WARN EBADENGINE   required: { node: '>=18' },
Notice: /Stage[main]/Splunk_otel_collector/Exec[Install splunk-otel-js]/returns: npm WARN EBADENGINE   current: { node: 'v16.20.2', npm: '8.19.4' }
Notice: /Stage[main]/Splunk_otel_collector/Exec[Install splunk-otel-js]/returns: npm WARN EBADENGINE }
Notice: /Stage[main]/Splunk_otel_collector/Exec[Install splunk-otel-js]/returns: npm notice 
Notice: /Stage[main]/Splunk_otel_collector/Exec[Install splunk-otel-js]/returns: npm notice New major version of npm available! 8.19.4 -> 11.4.0
Notice: /Stage[main]/Splunk_otel_collector/Exec[Install splunk-otel-js]/returns: npm notice Changelog: <https://github.com/npm/cli/releases/tag/v11.4.0>
Notice: /Stage[main]/Splunk_otel_collector/Exec[Install splunk-otel-js]/returns: npm notice Run `npm install -g [email protected]` to update!
Notice: /Stage[main]/Splunk_otel_collector/Exec[Install splunk-otel-js]/returns: npm notice 
Notice: /Stage[main]/Splunk_otel_collector/Exec[Install splunk-otel-js]/returns: npm ERR! code 1

Updating all nodejs version references to v18.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 44.46%. Comparing base (28afaf8) to head (96eef97).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6238      +/-   ##
==========================================
+ Coverage   44.38%   44.46%   +0.07%     
==========================================
  Files         390      390              
  Lines       26986    26986              
==========================================
+ Hits        11979    12000      +21     
+ Misses      14162    14145      -17     
+ Partials      845      841       -4     

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