optimize: ContextCoreLoader.java code style

[EZKAYOTWJPRKXWCUYEEB]

Ⅰ. Describe what this PR did

Ⅱ. Does this pull request fix one issue?

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

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov-io]

Codecov Report

Merging #2224 into develop will decrease coverage by <.01%.
The diff coverage is 100%.

@@              Coverage Diff              @@
##             develop    #2224      +/-   ##
=============================================
- Coverage      53.07%   53.06%   -0.01%     
- Complexity      2501     2502       +1     
=============================================
  Files            485      485              
  Lines          15304    15299       -5     
  Branches        1755     1754       -1     
=============================================
- Hits            8122     8119       -3     
+ Misses          6407     6405       -2     
  Partials         775      775

Impacted Files	Coverage Δ	Complexity Δ
.../java/io/seata/core/context/ContextCoreLoader.java	100% <100%> (+42.85%)	1 <1> (ø)	⬇️
...server/store/file/FileTransactionStoreManager.java	56.5% <0%> (-0.96%)	29% <0%> (ø)
.../io/seata/core/context/ThreadLocalContextCore.java	28.57% <0%> (+28.57%)	1% <0%> (+1%)	⬆️

[zjinlei]

LGTM

[slievrly]

LGTM

[funky-eyes]

https://cla-assistant.io/seata/seata 请打开cla链接签署，感谢配合