Cleans up the build process for improved consistency:

Build

• changes to use ./mvnw everywhere, rather than mix-and-matching "maven version installed on github actions default runner" with "maven version implied by wrapper" and "maven version I have installed locally"
  • suggests people use the wrapper for consistency.
  • this PR on its own might be marginally slower than before, but should be neutral when combined with [10.0] build: bump maven from 3.9.11 to 3.9.14 via script-only style #9316 since that avoids another JVM bootstrap for the wrapper
• uses --no-transfer-progress/-ntp consistently rather than mixing with --batch-mode/-B in some places.
• removes some ancient travis and ant/ivy scripting

GitHub Actions

• upgrades github actions versions to latest
  • locking specific actions hashes is considered better practice for supply chain paranoia and reproducibility, however we'd need dependabot/renovate automation to make that maintainable, and it's partially moot if the release build isn't produced off GitHub Actions, and thus likely not reproducible.
• removes useless/json-schema-violating strategy without matrix
• (for discussion!) changes the reusable publish-snapshots.yml workflow to run with the version implied by the repo and branch/revision the actions are running on rather than locking to some jruby/jruby revision
  • its a bit confusing to use a version of one workflow implied by a completely different commit to the caller. When reusing workflows inside the same repo; I believe it's generally more canonical to use whichever version is defined by the current checked actions. Doing it this way makes it easier to
  • test/refactor/sanity test these actions on ones own fork
  • review all the workflow yaml that will be run alongside each other
  • in future, avoid needing to pass in things like the javaLevel - each branch can define its targets/matrix independently in its workflows.
  • the build process becomes more consistently source controlled alongside the source being built (except for defining GHA schedules which only apply off master).