metrics: bump CSE for columnar meta cache metrics and fix prefetch cache hit panel unit

[JaySon-Huang]

Enhancement

As a TiFlash operator / developer, I want TiFlash Summary to reflect the latest columnar meta-cache observability from cloud-storage-engine, and to display prefetch cache hit correctly.

Motivation

• cloud-storage-engine added columnar meta cache metrics (hit/miss/parse/entries/weighted size) that TiFlash CN/proxy should expose through the bumped submodule.
• tiflash_proxy_kv_engine_columnar_prefetch_cache_hit observes hit_ratio * 100 with linear percent buckets (50,52,...,98,+Inf), but TiFlash Summary currently draws it with duration_panel (seconds) and a misleading "Duration" title, which misrepresents the metric as latency.

Proposal

1. Bump contrib/cloud-storage-engine to a revision that includes the columnar meta cache metrics, and refresh related Cargo.lock / proxy build notes as needed.
2. In TiFlash Summary, rename the panel to Columnar Prefetch Cache Hit Ratio and plot histogram quantiles with Y-axis unit percent (0–100) instead of seconds.

Acceptance

• TiFlash builds against the bumped CSE submodule.
• TiFlash Summary shows prefetch cache hit as a percent ratio distribution (not duration).
• Meta cache related metrics from the bumped CSE revision are available via tiflash_proxy_kv_engine_columnar_meta_cache_*.