Updated YCQL driver, updated jepsen version and added print random seed (#125)

* Replace `rand-` calls with `jepsen.random` functions and upgrade Jepsen dependency to 0.3.10

* Set `JAVA_HOME` in Jepsen test runner to `/usr/lib/jvm/zulu-25.jdk`.

* Update `JAVA_HOME` to `/usr/lib/jvm/zulu-21.jdk` and log Java version in Jepsen test runner

* Set `JAVA_HOME` in Jepsen test runner to `/usr/lib/jvm/zulu-17.jdk`.

* Exclude `slf4j-api` from `cassaforte` and add explicit dependency on `slf4j-api 2.0.17`.

* Migrate from Cassaforte to DataStax Java Cassandra driver and refactor YCQL client utilities accordingly.

* Replace `cu/ls` with `cu/exists?` in post-install script assertion for improved clarity and reliability.

* Persist random seed in test map and update `cu/ls` usage for full path handling in `log-files`.

* Update default concurrency in Jepsen test runner from `4n` to `6n`

Author: qvad

yugabyte/run-jepsen.py

@@ -381,7 +381,7 @@ def parse_args():
         help='Enable clock skew nemesis. This will not work on LXC.')
     parser.add_argument(
         '--concurrency',
-        default='4n',
+        default='6n',
         help='Concurrency to specify, e.g. 2n, 4n, or 5n, where n means the number of nodes.')
     parser.add_argument(
         '--workloads',