chore: extend developer dashboard; add k6 load test

[crandles]

Splitting out changes from #925; it is simpler if these changes are in main to do comparisons

• test: add k6 load test script
  • basic, but helpful so far. should be able to extend
• chore: [docs/dashboards] add redis datasource to grafana
• chore: [docs/dashboards] add more memory & request duration panels
  • added: "GOMAXPROCS" stat, 2 extra memory stats, cpu usage, go gc duration, processed bytes, frontend request duration histogram, + overall request duration histogram
  • (processed bytes not working via darwin at this time)

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New Panels:

more new panels: