Make Autotest compatible with the new version of dpdispatcher.

[AnguseZhang]

The purpose of this PR is:

1. Fix bugs such that dpgen autotest can run with the new version of dpdispatcher, instead of Dispatcher implemented in DP-GEN.
2. Delete multiprocessing in common_equi, such that there's only one dispatcher in this function. Meantime, we still keep multiprocessing in common_prop, and each property will have one dispatcher.

[codecov-commenter]

Codecov Report

Merging #667 (b460d0b) into devel (7d2c1de) will increase coverage by 0.03%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##            devel     #667      +/-   ##
==========================================
+ Coverage   33.92%   33.95%   +0.03%     
==========================================
  Files          86       86              
  Lines       15432    15415      -17     
==========================================
- Hits         5235     5234       -1     
+ Misses      10197    10181      -16     

Impacted Files	Coverage Δ
dpgen/auto_test/common_equi.py	61.48% <0.00%> (+6.57%)	⬆️
dpgen/auto_test/common_prop.py	38.25% <0.00%> (-0.26%)	⬇️

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