Fix bug: Closing iterators on errors for CassandraTable and MysqlTable

[vamossagar12]

Fix #1983

[vamossagar12]

hi @javeme . Plz review. I noticed a similar issue for MysqlTable so added that as well as part of the PR

[codecov]

Codecov Report

Merging #2014 (6f9acd3) into master (020b7dc) will increase coverage by 0.00%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             master    #2014    +/-   ##
==========================================
  Coverage     66.35%   66.36%            
- Complexity      677      978   +301     
==========================================
  Files           482      482            
  Lines         41449    41457     +8     
  Branches       5890     5890            
==========================================
+ Hits          27505    27512     +7     
- Misses        11244    11248     +4     
+ Partials       2700     2697     -3     

Impacted Files	Coverage Δ
...egraph/backend/store/cassandra/CassandraTable.java	79.05% <0.00%> (-1.09%)	⬇️
...aidu/hugegraph/backend/store/mysql/MysqlTable.java	82.66% <0.00%> (-0.80%)	⬇️
...va/com/baidu/hugegraph/util/collection/IntMap.java	72.80% <0.00%> (+0.39%)	⬆️
...va/com/baidu/hugegraph/backend/cache/RamCache.java	73.48% <0.00%> (+0.55%)	⬆️
...om/baidu/hugegraph/backend/store/BackendTable.java	85.11% <0.00%> (+0.59%)	⬆️
...in/java/com/baidu/hugegraph/schema/IndexLabel.java	77.27% <0.00%> (+1.13%)	⬆️
...va/com/baidu/hugegraph/task/ServerInfoManager.java	75.00% <0.00%> (+1.74%)	⬆️

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[javeme]

Thanks for your contribution

[vamossagar12]

Thanks for your contribution

Thanks @javeme . I made the changes.