Expose some etcd configuration in the spec

[vivek-koppuru]

What would you like to be added:
Add the ability to expose etcd options, like increasing the etcd DB size by modifying the ETCD_QUOTA_BACKEND_BYTES variable in the /etc/etcd/etcd.env file.

Why is this needed:
Modifying this file requires modifying each etcd node, restarting the server, and doing a compact and defrag for changes to be reflected. This could be automated through the bootstrapping phase.

Workarounds:

• make the change manually
• modify the template prior to bootstrapping cluster, or upgrading the template in the spec with this change baked in as part of automation through image-builder
• look into why DB is taking so much space as the default recommended is usually 2GB, so should look into what is taking up space by following this: https://etcd.io/blog/2023/how_to_debug_large_db_size_issue/