perf: avoid cache during compaction

[v0y4g3r]

I hereby agree to the terms of the GreptimeDB CLA.

Refer to a related PR or issue link (optional)

What's changed and what's your intention?

This pr fixes the memory consumption issue during log ingestion. From prior benchmark, we observed unexpected memory usage which won't be reclaimed even after stopping benchmark and flushing all pending data to disk.

In memory profiling we can see that it's related to merge reader that caches row group data. This behavior is necessary in normal query paths, but not desired in compaction, in that the files read during compaction will be deleted shortly after compaction.
This can also be confirmed through metrics:

$ curl -s -XGET localhost:4000/metrics | grep page
greptime_mito_cache_bytes{type="page"} 3776304887

Memory usage after this fix

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR requires documentation updates.

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[codecov]

Codecov Report

Attention: Patch coverage is 85.41667% with 14 lines in your changes missing coverage. Please review.

Project coverage is 84.04%. Comparing base (ce86ba3) to head (bb8d9f2).
Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5135   +/-   ##
=======================================
  Coverage   84.03%   84.04%           
=======================================
  Files        1168     1168           
  Lines      217572   217640   +68     
=======================================
+ Hits       182841   182916   +75     
+ Misses      34731    34724    -7     

[fengjiachun]

LGTM

[fengjiachun]

Nit: If there was a NoopCacheManager, we wouldn't need to modify so much code.