fix: insert disk cache on hybrid cache fetch miss

[MrCroxx]

What's changed and what's your intention?

Please explain IN DETAIL what the changes are in this PR and why they are needed. :D

Previously, foyer inserts disk cache on in-memory cache eviction. After v0.9.x, foyer inserts disk cache on hybrid cache insertion. But fetch() only calls insert on in-memory cache, not hybrid cache insert().

This PR fixes the bug by proactively inserting the disk cache on hybrid fetch miss.

Benchmark (new baseline)

rm -rf /6536/foyer && cargo build --release && RUST_BACKTRACE=1 RUST_LOG=info ./target/release/foyer-bench --dir /6536/foyer --mem 64 --disk 102400 --file-size 64 --get-range 10000 --flushers 4 --reclaimers 4 --time 60 --writers 256 --w-rate 4 --admission-rate-limit 500 --readers 1024 --r-rate 1 --runtime --compression none --distribution zipf --distribution-zipf-s 0.8 --metrics

Total:
disk total iops: 3513.0
disk total throughput: 582.8 MiB/s
disk read iops: 1236.9
disk read throughput: 82.1 MiB/s
disk write iops: 2276.1
disk write throughput: 500.7 MiB/s
insert iops: 14290.2/s
insert throughput: 893.2 MiB/s
insert lat p50: 4us
insert lat p90: 7us
insert lat p99: 17us
insert lat p999: 40us
insert lat p9999: 140us
insert lat p99999: 365us
insert lat pmax: 1011us
get iops: 17296.4/s
get miss: 8.41% 
get throughput: 1.0 GiB/s
get hit lat p50: 3us
get hit lat p90: 1023us
get hit lat p99: 3071us
get hit lat p999: 4415us
get hit lat p9999: 5663us
get hit lat p99999: 6783us
get hit lat pmax: 8319us
get miss lat p50: 92us
get miss lat p90: 919us
get miss lat p99: 2623us
get miss lat p999: 4047us
get miss lat p9999: 4895us
get miss lat p99999: 6111us
get miss lat pmax: 6111us

Checklist

• I have written the necessary rustdoc comments
• I have added the necessary unit tests and integration tests
• I have passed make all (or make fast instead if the old tests are not modified) in my local environment.

Related issues or PRs (optional)

risingwavelabs/risingwave#17473

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 4 lines in your changes missing coverage. Please review.

Project coverage is 86.10%. Comparing base (430e536) to head (96c5b37).

Files	Patch %	Lines
foyer/src/hybrid/cache.rs	85.18%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #591      +/-   ##
==========================================
- Coverage   86.14%   86.10%   -0.04%     
==========================================
  Files          59       59              
  Lines        7620     7631      +11     
==========================================
+ Hits         6564     6571       +7     
- Misses       1056     1060       +4     

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[Li0k]

LGTM, thanks for the fix