bugfix: fix get tablename and alias error in mysql delete

[jsbxyyx]

Ⅰ. Describe what this PR did

fix mysql delete with alias error.

Ⅱ. Does this pull request fix one issue?

fixes: #2626

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 #2628 into develop will decrease coverage by 0.00%.
The diff coverage is 33.33%.

@@              Coverage Diff              @@
##             develop    #2628      +/-   ##
=============================================
- Coverage      51.24%   51.24%   -0.01%     
- Complexity      2817     2819       +2     
=============================================
  Files            556      556              
  Lines          17803    17807       +4     
  Branches        2101     2102       +1     
=============================================
+ Hits            9123     9125       +2     
- Misses          7818     7820       +2     
  Partials         862      862              

Impacted Files	Coverage Δ	Complexity Δ
...a/sqlparser/druid/mysql/MySQLDeleteRecognizer.java	78.94% <33.33%> (-21.06%)	6.00 <1.00> (ø)
...in/java/io/seata/server/session/GlobalSession.java	84.16% <0.00%> (+0.45%)	72.00% <0.00%> (+1.00%)
...o/seata/server/coordinator/DefaultCoordinator.java	55.15% <0.00%> (+0.51%)	29.00% <0.00%> (+1.00%)

[zjinlei]

LGTM
Compared com.alibaba.druid.sql.parser.SQLStatementParser
parseUpdateStatement()
parseDeleteStatement()

[xingfudeshi]

LGTM.