bugfix: fix RetryRollbacking return NPE

[Bughue]

• I have registered the PR changes.

Ⅰ. Describe what this PR did

allSessions/findGlobalSessions 都有可能返回null，不判断的话可能导致npe
现在发现两个方面有这个问题

1. 批量处理session（retry）
2. console相关的查询

Ⅱ. Does this pull request fix one issue?

fixes #4560

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 #4561 (39417c5) into develop (496d08c) will increase coverage by 0.00%.
The diff coverage is 64.70%.

@@            Coverage Diff             @@
##             develop    #4561   +/-   ##
==========================================
  Coverage      49.44%   49.45%           
- Complexity      4070     4072    +2     
==========================================
  Files            732      732           
  Lines          25517    25521    +4     
  Branches        3152     3153    +1     
==========================================
+ Hits           12618    12621    +3     
  Misses         11555    11555           
- Partials        1344     1345    +1     

Impacted Files	Coverage Δ
...in/java/io/seata/server/session/SessionHelper.java	67.36% <0.00%> (-1.45%)	⬇️
...ver/storage/db/session/DataBaseSessionManager.java	36.84% <33.33%> (ø)
...rage/db/store/DataBaseTransactionStoreManager.java	61.44% <80.00%> (+2.40%)	⬆️
...o/seata/server/coordinator/DefaultCoordinator.java	54.09% <100.00%> (+0.37%)	⬆️
...very/registry/zk/ZookeeperRegisterServiceImpl.java	61.02% <0.00%> (-0.74%)	⬇️

[funky-eyes]

验证通过
LGTM

[slievrly]

LGTM