cache: apply per-volume settings on first start after clear

[masaori335]

Per-volume tuning (ram_cache, ram_cache_size, ram_cache_cutoff, avg_obj_size, fragment_size) was only copied onto the CacheVol when matching an existing on-disk volume, so volumes created fresh (e.g. the first start after a cache clear) ignored the config until the next restart. Apply the settings in one pass after all CacheVols exist.

Extend cache_volume_features to verify the settings take effect via per-volume metrics.

[Copilot]

Pull request overview

This PR fixes cache initialization so that per-volume tuning from storage.yaml (e.g., ram_cache, ram_cache_size, ram_cache_cutoff, avg_obj_size, fragment_size) is applied even when cache volumes are created fresh (such as the first startup after a cache clear), rather than only taking effect after a subsequent restart.

Changes:

• Apply per-volume configuration settings in a dedicated pass after all CacheVol instances are created/linked during cplist_reconfigure().
• Refactor the per-volume field-copying logic into a helper to keep cplist_update() focused on linking volumes.
• Extend the cache_volume_features gold test to validate behavior via per-volume metrics on a fresh cache.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/iocore/cache/CacheProcessor.cc	Applies per-volume config to CacheVol objects after creation/linking so fresh volumes don’t retain defaults until restart.
tests/gold_tests/cache/cache_volume_features.replay.yaml	Adds metric checks for per-volume RAM cache sizing and directory entry sizing to validate first-start behavior.
tests/gold_tests/cache/cache_volume_features.test.py	Updates the test summary to reflect the expanded coverage.

[masaori335]

[approve ci autest 1of4]