feature: support two-stage concurrent notification execution

[funky-eyes]

• I have registered the PR changes.

Ⅰ. Describe what this PR did

Ⅱ. Does this pull request fix one issue?

fixes #4627

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

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov-commenter]

Codecov Report

Merging #5118 (8e3eb00) into 2.x (e69627d) will increase coverage by 0.17%.
The diff coverage is 29.31%.

❗ Current head 8e3eb00 differs from pull request most recent head 9072591. Consider uploading reports for the commit 9072591 to get more accurate results

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@@             Coverage Diff              @@
##                2.x    #5118      +/-   ##
============================================
+ Coverage     48.73%   48.91%   +0.17%     
+ Complexity     4339     4170     -169     
============================================
  Files           778      741      -37     
  Lines         27454    26568     -886     
  Branches       3412     3305     -107     
============================================
- Hits          13380    12995     -385     
+ Misses        12677    12164     -513     
- Partials       1397     1409      +12     

Impacted Files	Coverage Δ
...c/main/java/io/seata/common/ConfigurationKeys.java	0.00% <ø> (ø)
...o/seata/server/coordinator/DefaultCoordinator.java	48.77% <0.00%> (+2.90%)	⬆️
...in/java/io/seata/server/session/SessionHelper.java	52.48% <25.00%> (-12.98%)	⬇️
...oconfigure/properties/server/ServerProperties.java	27.77% <40.00%> (-0.35%)	⬇️
.../java/io/seata/server/coordinator/DefaultCore.java	47.42% <50.00%> (-1.68%)	⬇️

... and 204 files with indirect coverage changes

[CLAassistant]

All committers have signed the CLA.

[renliangyu857]

做成开关让用户配置，而不是默认并发，是出于什么考虑呢？

[funky-eyes]

保障如果代码有问题可以回退，后续稳定后可以考虑默认为true

[renliangyu857]

LGTM