Add properties required by Datastax Cassandra java driver v4

[findinpath]

Description

After transitioning to Cassandra java driver v4, the following properties
are required:

• cassandra.load-policy.use-dc-aware
• cassandra.load-policy.dc-aware.local-dc

Is this change a fix, improvement, new feature, refactoring, or other?

Documentation fix

Is this a change to the core query engine, a connector, client library, or the SPI interfaces? (be specific)

Cassandra connector

How would you describe this change to a non-technical end user or system administrator?

This PR adds a bit more documentation for the users of trino-cassandra after introducing #7828

Related issues, pull requests, and links

Related PR: #7828

Documentation

( ) No documentation is needed.
(x) Sufficient documentation is included in this PR.
( ) Documentation PR is available with #prnumber.
( ) Documentation issue #issuenumber is filed, and can be handled later.

Release notes

(x) No release notes entries required.
( ) Release notes entries required with the following suggested text:

# Section
* Fix some things. ({issue}`issuenumber`)

[mosabua]

So thats weird... its required but it has a default value? So can I leave it out and then it will just use the default? If that is the case.. its NOT required.. .. we need to clarify this here and in the release notes text

[ebyhr]

It has default value, but we need to enable it explicitly. We will consider changing the default value later.

[mosabua]

so this is NOT required then... lets remove it form the code snippet earlier

[ebyhr]

As we talked offline, changing the default value (false → true) is also fine to me.

[findinpath]

At the time of this writing, we use

trino/plugin/trino-cassandra/src/main/java/io/trino/plugin/cassandra/CassandraClientModule.java

Line 130 in 9f5357c

driverConfigLoaderBuilder.withString(DefaultDriverOption.LOAD_BALANCING_POLICY_CLASS, DefaultLoadBalancingPolicy.class.getName());

as the sole load balancing policy class:

should almost always be used; it requires a local datacenter to be specified either programmatically when creating the session, or via the configuration option: datastax-java-driver.basic.load-balancing-policy.local-datacenter. It can also use a highly efficient slow replica avoidance mechanism, which is by default enabled – see the option: datastax-java-driver.basic.load-balancing-policy.slow-replica-avoidance.

See https://github.com/datastax/java-driver/blob/4.x/core/src/main/resources/reference.conf

In the current context, I don't know whether the property cassandra.load-policy.use-dc-aware still makes sense.

[mosabua]

Needs clarification of what is actually required in docs and potentially in release notes

[mosabua]

Ideally we say this is required when use-dc-aware is true... but I am fine with the current status as well