doc: improve TM module Javadoc

[WangzJi]

• I have registered the PR changes.

Ⅰ. Describe what this PR did

This PR comprehensively enhances the English Javadoc documentation for Seata's Transaction Manager (TM) module to improve code readability and support international collaboration.

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]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 61.45%. Comparing base (4d58308) to head (d2ac90f).
⚠️ Report is 2 commits behind head on 2.x.

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x    #7462      +/-   ##
============================================
+ Coverage     61.21%   61.45%   +0.23%     
  Complexity      666      666              
============================================
  Files          1314     1314              
  Lines         49817    49817              
  Branches       5858     5858              
============================================
+ Hits          30497    30613     +116     
+ Misses        16575    16458     -117     
- Partials       2745     2746       +1     

Files with missing lines	Coverage Δ
...org/apache/seata/tm/DefaultTransactionManager.java	100.00% <ø> (ø)
.../apache/seata/tm/api/DefaultGlobalTransaction.java	73.98% <100.00%> (ø)
.../apache/seata/tm/api/GlobalTransactionContext.java	100.00% <ø> (ø)
...org/apache/seata/tm/api/TransactionalExecutor.java	64.28% <ø> (ø)
...org/apache/seata/tm/api/TransactionalTemplate.java	57.45% <ø> (ø)
...g/apache/seata/tm/api/transaction/Propagation.java	100.00% <ø> (ø)
...ache/seata/tm/api/transaction/TransactionInfo.java	94.28% <ø> (ø)

... and 11 files with indirect coverage changes

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[slievrly]

LGTM