[APM] Optimize APM bundle

[sorenlouv]

Inspired by #67654 which optimized the infra bundle with 90% by introducing lazy loading we should attempt to do the same for APM.

Helpful comment from @weltenwort:

I used https://github.com/webpack-contrib/webpack-bundle-analyzer to analyze the webpack stats json files. To generate these files I used node scripts/build_kibana_platform_plugins.js --no-core --no-examples --profile --workers=2 with and without --dist before and after my changes

• Create webpack stats
  • node scripts/build_kibana_platform_plugins.js --no-core --no-examples --profile --workers=2 with and without --dist
• Find the APM bundle in x-pack/plugins/apm/target/public/apm.plugin.js. This should be as small as possible.
• To find ways to reduce the size of the APM bundle find the stats file in x-pack/plugins/apm/target/public/stats.js
• Analyze stats.json file using one of the two:
  • upload stats.json to https://chrisbateman.github.io/webpack-visualizer, or
  • run npx webpack-bundle-analyzer x-pack/plugins/apm/target/public/stats.json

[elasticmachine]

Pinging @elastic/apm-ui (Team:apm)

[sorenlouv]

Fixed in #74740 by @shahzad31 !