Add possibility to build JanusGraph Scylla Release

Related to #3580

Signed-off-by: Oleksandr Porunov <alexandr.porunov@gmail.com>

docs/storage-backend/scylladb.md

@@ -79,8 +79,20 @@ compile "org.janusgraph:janusgraph-scylla:1.0.0"
     The manual process described below is temporary and should be replaced by automated process after the issue
     [janusgraph/janusgraph#3580](https://github.com/JanusGraph/janusgraph/issues/3580) is resolved.
 
-In case `scylla` storage option is needed to be used in JanusGraph distribution then it's necessary to replace the next libraries 
-in `lib` directory (all libraries can be downloaded via Maven Central Repository). 
+In case `scylla` storage option is needed to be used in JanusGraph distribution then it's necessary to replace the next 
+DataStax provided CQL driver with Scylla provided CQL driver.
+The default JanusGraph distribution builds contain only DataStax drivers, but not Scylla drivers because they are conflicting. 
+However, it's possible to build the same distribution build but with Scylla drivers enabled instead. 
+To do this, you can use the following command inside the JanusGraph repository:
+```groovy tab='Bash'
+mvn clean install -Pjanusgraph-release -Puse-scylla -DskipTests=true --batch-mode --also-make -Dgpg.skip=true
+```
+
+This command will generate distribution builds (both normal and full distribution build) in the 
+following directory: `janusgraph-dist/target/`.   
+
+Otherwise, if you can't build distribution on your own, you can use the JanusGraph provided distribution and replace 
+the following libraries in `lib` directory (all libraries can be downloaded via Maven Central Repository). 
 - `org.janusgraph:janusgraph-cql` with `org.janusgraph:janusgraph-scylla`
 - `org.janusgraph:cassandra-hadoop-util` with `org.janusgraph:scylla-hadoop-util`
 - `com.datastax.oss:java-driver-core` with `com.scylladb:java-driver-core`

janusgraph-dist/pom.xml

@@ -38,14 +38,42 @@
         <skipDefaultDistroIT>${it.skip}</skipDefaultDistroIT>
 
         <doc.dir>${project.parent.basedir}/docs</doc.dir>
+
+        <cql-module>janusgraph-cql</cql-module>
+        <cql-hadoop-module>cassandra-hadoop-util</cql-hadoop-module>
     </properties>
 
     <dependencies>
         <dependency>
             <groupId>${project.groupId}</groupId>
             <artifactId>janusgraph-all</artifactId>
             <version>${project.version}</version>
+            <exclusions>
+                <exclusion>
+                    <artifactId>janusgraph-cql</artifactId>
+                    <groupId>${project.groupId}</groupId>
+                </exclusion>
+                <exclusion>
+                    <artifactId>cassandra-hadoop-util</artifactId>
+                    <groupId>${project.groupId}</groupId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+
+        <!-- Either "janusgraph-cql" or "janusgraph-scylla" -->
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>${cql-module}</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+
+        <!-- Either "cassandra-hadoop-util" or "scylla-hadoop-util" -->
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>${cql-hadoop-module}</artifactId>
+            <version>${project.version}</version>
         </dependency>
+
         <dependency>
             <groupId>net.java.dev.jna</groupId>
             <artifactId>jna</artifactId>
@@ -326,6 +354,13 @@
                 <docker.tag-suffix>-java-11</docker.tag-suffix>
             </properties>
         </profile>
+        <profile>
+            <id>use-scylla</id>
+            <properties>
+                <cql-module>janusgraph-scylla</cql-module>
+                <cql-hadoop-module>scylla-hadoop-util</cql-hadoop-module>
+            </properties>
+        </profile>
         <profile>
             <id>janusgraph-release</id>
             <dependencies>