meta: keep valid utf8 in dumped JSON

[zhijian-pro]

Close #1754

[codecov-commenter]

Codecov Report

Merging #1973 (b254b54) into main (975011b) will increase coverage by 0.01%.
The diff coverage is 87.50%.

@@            Coverage Diff             @@
##             main    #1973      +/-   ##
==========================================
+ Coverage   61.59%   61.61%   +0.01%     
==========================================
  Files         135      135              
  Lines       23580    23581       +1     
==========================================
+ Hits        14525    14529       +4     
+ Misses       7375     7373       -2     
+ Partials     1680     1679       -1     

Impacted Files	Coverage Δ
pkg/meta/dump.go	76.27% <87.50%> (+0.40%)	⬆️
pkg/meta/sql_lock.go	72.43% <0.00%> (-2.57%)	⬇️
pkg/chunk/cached_store.go	76.05% <0.00%> (-0.19%)	⬇️
pkg/object/azure.go	1.72% <0.00%> (+0.02%)	⬆️
pkg/meta/redis.go	71.88% <0.00%> (+0.04%)	⬆️
pkg/chunk/disk_cache.go	80.33% <0.00%> (+0.48%)	⬆️
pkg/chunk/utils_unix.go	93.33% <0.00%> (+20.00%)	⬆️

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