Throw exception instead of ignoring connection string scheme or parameters

Suggested release note:

`Cluster.connect` now throws an `IllegalArgumentException` if you pass a pre-built `ClusterEnvironment` and a connection string incompatible with the environment.

• A pre-built environment without TLS enabled is incompatible with a connection string that specifies the secure `couchases` scheme.
• A pre-built environment is incompatible with a connection string that has parameters.

Before this change, the connection string scheme and parameters were always silently ignored when connecting with a pre-built cluster environment.