Fix NPM on Oracle 12.2 when load column metadata

[CLSChenml]

Fixes #23013 .

Changes proposed in this pull request:

• Added null value handling to resolve NPM issues when obtaining metadata in Oracle12.2 environment.
• Added unit test for it.

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• My code follows the code of conduct of this project.
• I have self-reviewed the commit code.
• I have (or in comment I request) added corresponding labels for the pull request.
• I have passed maven check locally : ./mvnw clean install -B -T1C -Dmaven.javadoc.skip -Dmaven.jacoco.skip -e.
• I have made corresponding changes to the documentation.
• I have added corresponding unit tests for my changes.

[codecov-commenter]

Codecov Report

Merging #23432 (7e3480b) into master (0de54e9) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master   #23432      +/-   ##
============================================
- Coverage     49.83%   49.82%   -0.01%     
  Complexity     2461     2461              
============================================
  Files          4081     4080       -1     
  Lines         58280    58276       -4     
  Branches       9253     9253              
============================================
- Hits          29041    29035       -6     
- Misses        26683    26684       +1     
- Partials       2556     2557       +1     

Impacted Files	Coverage Δ
...ema/loader/dialect/OracleSchemaMetaDataLoader.java	86.90% <100.00%> (+0.15%)	⬆️
...ontend/executor/ConnectionThreadExecutorGroup.java	73.33% <0.00%> (-13.34%)	⬇️
...gsphere/agent/core/plugin/jar/PluginJarLoader.java	0.00% <0.00%> (ø)
.../plugin/yaml/loader/PluginConfigurationLoader.java
...or/config/AdvisorConfigurationRegistryFactory.java
...advisor/yaml/entity/YamlAdvisorsConfiguration.java
...yaml/swapper/YamlAdvisorsConfigurationSwapper.java
...advisor/yaml/entity/YamlPointcutConfiguration.java
...aml/entity/YamlPointcutParameterConfiguration.java
...r/yaml/loader/YamlAdvisorsConfigurationLoader.java
... and 24 more

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