Use a 'matrix' strategy for LFRic integration tests

[arporter]

Currently we have a lot of duplication in our LFRic integration tests. Some of this could be removed if we changed to using a 'matrix' strategy as discussed here: https://github.com/stfc/PSyclone/pull/2733#discussion_r1787858105_

This will be slightly involved as it will require us to replace 'steps' with 'jobs'.