make sccache -s always return current cache size

[iTrooz]

sccache server disk cache is usually initiated by the first compilation request. If sccache -s is issued before then, sccache will not return the currently occupied cache size. This PR fixes that by querying the underlying LruDiskCache in current_size(). I don't think there are performance implications of this, but I am not sure.

I also renamed LazyDiskCache to LazyLruDiskCache, because I think the name is more clear. Let me know if you want me to revert that change

[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.30435% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.18%. Comparing base (3fe258a) to head (b71fe2c).

Files with missing lines	Patch %	Lines
src/cache/disk.rs	83.33%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2419   +/-   ##
=======================================
  Coverage   71.18%   71.18%           
=======================================
  Files          64       65    +1     
  Lines       35592    35603   +11     
=======================================
+ Hits        25335    25343    +8     
- Misses      10257    10260    +3     

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[iTrooz]

Hello, do you need me to do something on this PR ?

[codspeed-hq]

Merging this PR will not alter performance

✅ 27 untouched benchmarks
⏩ 2 skipped benchmarks¹

---

_{Comparing iTrooz:always_show_cache (b71fe2c) with main (3fe258a)}

Footnotes

1. 2 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[iTrooz]

@sylvestre Hello ! I keep seeing pushes made to this PR. Do you need me to do something on it, or are you just testing it ?

[sylvestre]

I was just running the benchmarks again

[iTrooz]

Ok ! Lmk if anything prevents this from being merged