fix(net): optimze test cases to make coverage stable

[317787106]

What does this PR do?

• optimize some test case, so that test case's coverage of same code will stay the same.
• fix the bug that oom occurs when run all test cases

Why are these changes required?

• sometimes, the coverage of the same code in one machine may change because of network latency.
• sometimes, the coverage of the same code in different machines may change.

This PR has been tested by:

• Unit Tests
• Manual Testing

Follow up

Extra details

[codecov-commenter]

Codecov Report

Merging #5133 (7a8ceee) into release_v4.7.2 (cc9a944) will increase coverage by 0.04%.
The diff coverage is 100.00%.

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@@                 Coverage Diff                  @@
##             release_v4.7.2    #5133      +/-   ##
====================================================
+ Coverage             56.95%   56.99%   +0.04%     
- Complexity             8521     8533      +12     
====================================================
  Files                   836      836              
  Lines                 49602    49603       +1     
  Branches               5518     5518              
====================================================
+ Hits                  28249    28271      +22     
+ Misses                19068    19051      -17     
+ Partials               2285     2281       -4     

Impacted Files	Coverage Δ
...rc/main/java/org/tron/core/net/TronNetService.java	87.23% <100.00%> (+0.13%)	⬆️

... and 12 files with indirect coverage changes

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