Verify that backwards-compatibility versions are in sync across branches in CI

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Is your feature request related to a problem? Please describe.

When incrementing a version for OpenSearch we have to update multiple files across multiple branches.

• https://github.com/opensearch-project/OpenSearch/blob/main/.ci/bwcVersions
• https://github.com/opensearch-project/OpenSearch/blob/main/buildSrc/version.properties
• https://github.com/opensearch-project/OpenSearch/blob/main/server/src/main/java/org/opensearch/Version.java

These enable backwards-compatibility testing across multiple versions.

The process has been automated (https://github.com/opensearch-project/OpenSearch/blob/main/.github/workflows/version.yml), however it's brittle. It's also easy to make a mistake when making an unrelated change. As an example,. #2430 has fixed one of those mistakes.

Describe the solution you'd like
Check version, constants and bcw versions in CI.

Additional context
Discussed in #2532 (comment)