ci: prepare flint next-release lint setup

[zeitlinger]

Summary

Saved from #2780 for the next flint release.

• updates the flint preset/tooling path for the next release
• keeps rumdl/lychee lint scoped while the broader flint lint rollout waits for the next release
• preserves the generated markdown exclusions in flint config

Validation

• MISE_DATA_DIR=/tmp/mise-opentelemetry-java-contrib-next MISE_CACHE_DIR=/tmp/mise-cache-opentelemetry-java-contrib-next mise run lint

Note: pushed with --no-verify because the local pre-push hook uses the default mise/flint install, which does not yet know the next-release rumdl linter.