Update Horizon Docker image to support P19

[jcx120]

Update Captive Core in Horizon Docker image to support P19 version.

[2opremio]

To solve the docker build caching problems we have, I think we should just add a build parameter with core's version. This will make docker cache things correctly.

Also, the horizon docker image tag should probably reflect the core version included (otherwise we may end up releasing mutable tags, i.e. different images with the same tag but different core versions).

[leighmcculloch]

@2opremio There is conversation about this here: #4379 (comment)

[2opremio]

@leighmcculloch thanks, I reposted it there.

[jcx120]

Closing this issue as its being addressed in #4379 (for removing cache)
Current Docker image also updated to unblock users.

[bartekn]

GH didn't autoclose?