store: remove noisy labelvalues internal spans per block

[adezxc]

continuation of #8954 Drop bucket_store_block_label_values as it was as well very noisy.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.50%. Comparing base (b453e37) to head (d567cbc).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8979      +/-   ##
==========================================
- Coverage   64.54%   64.50%   -0.05%     
==========================================
  Files         289      289              
  Lines       37359    37352       -7     
==========================================
- Hits        24115    24094      -21     
- Misses      11151    11160       +9     
- Partials     2093     2098       +5     

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