feat: update add-on after migration to ddev org

[stasadev]

The Issue

• Consider making this official and moving to github.com/ddev #1

How This PR Solves The Issue

1. I want to become a maintainer because I use OpenSearch (and have my own config), but I never knew about this add-on.
2. Update tests.yml to the latest one.
3. Update docker-compose.opensearch.yaml:

• remove version, networks, links as not needed
• remove hostname - I never actually set this setting, and didn't see it in the official DDEV add-ons
• rename ES_JAVA_OPTS to OPENSEARCH_JAVA_OPTS
• use cluster.name and node.name from the official docs.
• remove SERVER_NAME from opensearch-dashboards - I don't know why this needed.
• add healthcheck

Manual Testing Instructions

Automated Testing Overview

Related Issue Link(s)

Release/Deployment Notes

[stasadev]

@cmuench, let me know if you agree with any of these changes.

This will be a major 2.0.0 release, because I made some changes to the names of some variables (according to the official OpenSearch docs) and I don't know if it's compatible with existing installations of this add-on.

[cmuench]

Looks good

[stasadev]

Thanks and one more thing that I noticed just now, there is no LICENSE file.
Is it okay to use this one?
https://github.com/ddev/ddev-addon-template/blob/main/LICENSE

[cmuench]

Thanks and one more thing that I noticed just now, there is no LICENSE file. Is it okay to use this one? https://github.com/ddev/ddev-addon-template/blob/main/LICENSE

I am a big fan of MIT license but the Apache license is also OK for me. If it's the default for ddev addons then let's use it.