Add possibility to build JanusGraph Scylla Release

[porunov]

The idea in this PR is to add another profile which replaces janusgraph-cql with janusgraph-scylla when activated. Thus, allowing users to build a distribution release either with DataStax drivers or Scylla drivers.

Building distribution with CQL libs in this PR is the same as we have in our release workflow:

mvn clean install -Pjanusgraph-release -DskipTests=true --batch-mode --also-make -Dgpg.skip=true

Building distribution with Scylla libs in this PR requires activating additional profile use-scylla:

mvn clean install -Pjanusgraph-release -Puse-scylla -DskipTests=true --batch-mode --also-make -Dgpg.skip=true

Update: moved previous discussion message into the following comment, so that this PR focuses on adding possibility to build a distribution release with Scylla libraries instead of copy pasting them manually.
This PR is not about improving our current published JanusGraph distribution builds or adding support to Docker to run Scylla. Docker and published distribution builds can be improved in follow up PRs.

Related to #3580

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[farodin91]

It would be interesting to build both docker images with a different tag or?

[porunov]

It would be interesting to build both docker images with a different tag or?

I think we don’t necessarily need 2 docker releases (one for Scylla and another one for CQL). Instead, as I described in the referenced issue we can have an environment variable which controls if Scylla drivers or CQL drivers are used.
However, I’m OK to have a separate Docker image with ScyllaDB.
In this PR I’m just adding the ability to manually build 2 different distributions (one with DayaStax drivers and another one with Scylla drivers).

[farodin91]

LGTM. Thank you.