feat: remove index when storage lookup miss

[MrCroxx]

What's changed and what's your intention?

As titled.

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• I have passed make check and make test in my local envirorment.

Related issues or PRs (optional)

close #94

[codecov]

Codecov Report

Merging #99 (dbf02a4) into main (d3b2972) will increase coverage by 0.80%.
Report is 2 commits behind head on main.
The diff coverage is 96.46%.

@@            Coverage Diff             @@
##             main      #99      +/-   ##
==========================================
+ Coverage   66.80%   67.60%   +0.80%     
==========================================
  Files          40       41       +1     
  Lines        4944     5091     +147     
==========================================
+ Hits         3303     3442     +139     
- Misses       1641     1649       +8     

Files Changed	Coverage Δ
foyer-intrusive/src/eviction/mod.rs	64.70% <ø> (ø)
foyer-storage/src/region_manager.rs	94.56% <ø> (-0.06%)	⬇️
foyer-intrusive/src/eviction/sfifo.rs	95.85% <95.85%> (ø)
foyer-intrusive/src/eviction/fifo.rs	94.00% <100.00%> (-1.82%)	⬇️
foyer-memory/src/lib.rs	98.55% <100.00%> (ø)
foyer-storage/src/store.rs	83.64% <100.00%> (+0.05%)	⬆️