Drop Ember < 3.28 and node < 16

[BlueCutOfficial]

This PR is a step of the conversion to v2 addon.

• It removes the support for Ember < 3.28
• It removes support for node < 16

Why?
Once the addon is converted to v2, the ember-try scenario start failing for Ember < 3.28. Also, the addon will require dependencies like [email protected] (to support static blocks) that require at least node 16.

Additionally, the PR:

• resets the jquery-integration to false.
• downgrade a node version to 16 in the CI to make sure 16 is still supported.

[pichfl]

Thanks for tackling this! I don't think we've ever needed the jQuery integration for this addon anyway, so this is a welcome change.