Make CQL METADATA_SCHEMA_WINDOW programatically configurable

**Describe the feature:**
`METADATA_SCHEMA_WINDOW` is hardcoded but sometimes users might want to increase this value in case they create new graphs dynamically.

Temporal solution is overwriting JanusGraph CQL configuration using `storage.cql.internal`. I.e. something like:
```
storage.cql.internal.string-configuration = "datastax-java-driver { advanced.metadata.schema.debouncer.window = 1 second }"
```

**Describe a specific use case for the feature:**
The issue users might experience with this configuration being hard-coded could be found here: https://lists.lfaidata.foundation/g/janusgraph-users/topic/85741983

Start by tracing JanusGraph's CQL configuration handling and locating the hardcoded METADATA_SCHEMA_WINDOW value. Review how storage.cql.internal currently passes Datastax driver settings, and consider the issue complete when this window can be configured without overwriting the broader internal configuration.

Written by the indexing model from the issue text.