[cherry-pick]reduce compact parallel task num

[weiliu1031]

pr: #27899

/kind improvement

to reduce the memory cost during compact, reduce the compact parallel task num

[mergify]

@weiliu1031 E2e jenkins job failed, comment /run-cpu-e2e can trigger the job again.

[congqixia]

/lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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[codecov]

Codecov Report

Merging #27900 (141cbec) into 2.2.0 (ce17962) will decrease coverage by 0.01%.
Report is 1 commits behind head on 2.2.0.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##            2.2.0   #27900      +/-   ##
==========================================
- Coverage   80.96%   80.96%   -0.01%     
==========================================
  Files         745      745              
  Lines      109255   109254       -1     
==========================================
- Hits        88459    88457       -2     
- Misses      17446    17452       +6     
+ Partials     3350     3345       -5     

Files	Coverage Δ
internal/datanode/flow_graph_dd_node.go	82.62% <100.00%> (+0.92%)	⬆️
internal/util/paramtable/component_param.go	87.37% <100.00%> (ø)

... and 14 files with indirect coverage changes

[weiliu1031]

/run-cpu-e2e