test: Increase [integration-tx-api] module test case coverage

[azatyamanaev]

• I have registered the PR changes.

Ⅰ. Describe what this PR did

increase test case coverage of [integration-tx-api] module

Ⅱ. Does this pull request fix one issue?

fixes #6507

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[xingfudeshi]

Pls register this PR in https://github.com/apache/incubator-seata/tree/2.x/changes

[azatyamanaev]

Pls register this PR in https://github.com/apache/incubator-seata/tree/2.x/changes

@xingfudeshi Done

[azatyamanaev]

@xingfudeshi Can you resolve merge conflict?

[xingfudeshi]

@xingfudeshi Can you resolve merge conflict?

Yes.The current version is being released.I'll resolve conflicts after the release.

[azatyamanaev]

@xingfudeshi Can you resolve merge conflict?

Yes.The current version is being released.I'll resolve conflicts after the release.

How long does it usually take?

[xingfudeshi]

@xingfudeshi Can you resolve merge conflict?

Yes.The current version is being released.I'll resolve conflicts after the release.

How long does it usually take?

It won’t take long. After version 2.1 is released, I will start addressing the conflicting files in this PR.

[lightClouds917]

please resolve the conflict

[azatyamanaev]

please resolve the conflict

I can't, I don't have write access to repository. Or should I rebase my branch?

[lightClouds917]

please resolve the conflict

I can't, I don't have write access to repository. Or should I rebase my branch?
you can merge the 2.x branch to your branch,and resolve the confict.

[justinmclean]

I've fixed the conflicts for you.

[lightClouds917]

LGTM

[funky-eyes]

我修复了codecov没有report成功的问题，现在让我们看看目前的单测覆盖度是多少
I've fixed the issue with Codecov not reporting successfully. Now, let's see what the current test coverage percentage is.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 50.47%. Comparing base (20cd962) to head (3ebc46d).

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x    #6533      +/-   ##
============================================
+ Coverage     50.02%   50.47%   +0.44%     
- Complexity     5734     5830      +96     
============================================
  Files          1051     1051              
  Lines         36340    36340              
  Branches       4321     4319       -2     
============================================
+ Hits          18179    18341     +162     
+ Misses        16365    16183     -182     
- Partials       1796     1816      +20     

Files	Coverage Δ
...ta/integration/tx/api/remoting/TwoPhaseResult.java	100.00% <100.00%> (+100.00%)	⬆️

... and 14 files with indirect coverage changes

[funky-eyes]

LGTM