Remove unused systemd service files

[Earlopain]

Is your feature request related to a problem? Please describe.
I was looking into the service files in this repo and was surprised that they don't match what got installed on the system.
https://github.com/opensearch-project/OpenSearch/blob/main/distribution/packages/src/common/systemd/opensearch.service

The actual file seems to originate from the build repo here:
https://github.com/opensearch-project/opensearch-build/blob/main/scripts/pkg/service_templates/opensearch/usr/lib/systemd/system/opensearch.service

Describe the solution you'd like
Remove the unused service files to reduce potential confusion.

[gaiksaya]

Hi @peterzhuamazon Can you take a look at this? Wondering if the other service file is required starting min distribution independently of the distribution.

Thanks!