Remove custom build.sh script

[epugh]

Now that UBI is part of the standard release process, I think but don't know, that we can remove scripts/build.sh.

[sandeshkr419]

[Search Triage] @gaiksaya @Divyaasm Can you please help clarify this?

[gaiksaya]

If it matches the default script used for building and gets the work done, the script from this repo is safe to be removed.
Default build script: https://github.com/opensearch-project/opensearch-build/blob/main/scripts/default/opensearch/build.sh
Thanks!