[FEATURE] Bump open search version to 2.19 on 2.x

[rithin-pullela-aws]

Is your feature request related to a problem?

Set Opensearch version to 2.19 on 2.x branch of opensearch-learning-to-rank-base.
This is to prepare for the 2.19.0.0 release of LTR.

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[sandeshkr419]

@prudhvigodithi Is this already part of release automation process?

[prudhvigodithi]

[Triage]
Hey, moving forward this can be automated once the plugin is part of this workflow
https://github.com/opensearch-project/opensearch-build/blob/main/.github/workflows/os-increment-plugin-versions.yml, is this plugin target release is for 2.19? If so please follow the onboarding guide https://github.com/opensearch-project/opensearch-build/blob/main/ONBOARDING.md.
@gsingers @macohen @sstults @JohannesDaniel @rithin-pullela-aws
Thank you
@peterzhuamazon @getsaurabh02

[peterzhuamazon]

It should be 2.19.0.0, not 2.19.00.
With my initial talk with @rithin-pullela-aws the onboarding ticket needs to be opened at least 2 weeks before the first RC generation, which you can find the schedule here:
https://opensearch.org/releases.html