Change version in PluginInfo to V_2_19_0 after backport to 2.x merged

[cwperks]

Description

Small PR to change the version from V_3_0_0 to V_2_19_0 in PluginInfo after the backport of #16909 was merged to 2.x.

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

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[github-actions]

✅ Gradle check result for ac2f233: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 72.13%. Comparing base (ab546ae) to head (ac2f233).
Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
...c/main/java/org/opensearch/plugins/PluginInfo.java	0.00%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #16947      +/-   ##
============================================
- Coverage     72.23%   72.13%   -0.10%     
+ Complexity    65210    65182      -28     
============================================
  Files          5299     5299              
  Lines        303475   303496      +21     
  Branches      43925    43931       +6     
============================================
- Hits         219217   218937     -280     
- Misses        66254    66623     +369     
+ Partials      18004    17936      -68     

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