Switch to use scylla image instead of scylla version, to be able to target enterprise

[dkropachev]

Currently Makefile uses SCYLLA_VERSION to define docker image.
Switching to SCYLLA_IMAGE instead will help to target enterprise, nightly or custom image

[sylwiaszunejko]

I am okay with merging this commit: Switch to use scylla image instead of scylla version, to be able to target enterprise
I would just suggest change to the commit message to something like that:

Switch to use scylla image instead of scylla version

Currently Makefile uses SCYLLA_VERSION to define docker image.
Switching to SCYLLA_IMAGE instead will help to target enterprise, nightly or custom image

but the second commit shouldn't be in this PR

[dkropachev]

I am okay with merging this commit: Switch to use scylla image instead of scylla version, to be able to target enterprise I would just suggest change to the commit message to something like that:

Switch to use scylla image instead of scylla version

Currently Makefile uses SCYLLA_VERSION to define docker image.
Switching to SCYLLA_IMAGE instead will help to target enterprise, nightly or custom image

but the second commit shouldn't be in this PR

Commit leaked to master and I did not spot it right away, thanks, fixed