[Perf]: MOSS-Transcribe-Diarize model Encoder LRU cache

[nagisa-kunhah]

Motivation

Modifications

Related Issues

Accuracy Test

Benchmark & Profiling

Checklist

• [] Format your code according with pre-commit.
• Add unit tests.
• Update documentation / docstrings / example tutorials as needed.
• Provide throughput / latency benchmark results and accuracy evaluation results as needed.
• For reviewers: If you haven't made any contributions to this PR and are only assisting with merging the main branch, please remove yourself as a co-author when merging the PR.

CI

CI runs on self-hosted GPU runners and requires a maintainer to add the
run-ci label. Once labeled, every subsequent push re-triggers CI as
long as the label remains. Use /tag-and-rerun-ci higgs or
/tag-and-rerun-ci moss to select a TTS CI model. Draft PRs are skipped even
if labeled.