explore options to improve startup time

[kares]

• Bundler.setup seems to be taking ~3s (after https://github.com/elastic/logstash/pull/14284) there might be more that can be done, given that the LS' GEM_HOME only contains the minimal required gem set, Bundler's fast-loading (caching) mechanism should be reviewed, potentially profiling where time is spent

• Logstash bootstraping should be reviewed to load less (load some specific core features as needed) e.g. https://github.com/elastic/logstash/pull/13791/files

• locking (https://github.com/elastic/logstash/issues/10943) still relevant with recent Java/Logstash?

• explore the Java AOT feature (-XX:AOTLibrary) - warming up Logstash and saving the state

  • would potentially make sense to only pre-compile up to a point when the pipeline is being read
  • pre-compile the image for Linux only, image could be generated on installation or with a user command