[Spotless] Using custom Java formatter from k-nn plugin

[MitchellGale]

Description

Applied spotless on core/src/main/java/org/opensearch/sql/{expression, executor, datasource, data, analysis}

Fixes issue with Java doc seen in #312 by applying custom xml to format code instead of Google Java Formatter.

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (integ/sl_customFormatter@af12c02). Click here to learn what that means.
The diff coverage is n/a.

@@                     Coverage Diff                     @@
##             integ/sl_customFormatter     #315   +/-   ##
===========================================================
  Coverage                            ?   97.29%           
  Complexity                          ?     4572           
===========================================================
  Files                               ?      401           
  Lines                               ?    11180           
  Branches                            ?      810           
===========================================================
  Hits                                ?    10878           
  Misses                              ?      295           
  Partials                            ?        7           

Flag	Coverage Δ
sql-engine	97.29% <0.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

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