Change default serial consistency from `ANY` to `LOCAL_SERIAL`

[wprzytula]

The CPP Driver has the default serial consistency set to ANY. This results in the issue described in the Rust driver:

using lwt results in an error message: Consistency level for LWT is missing for a request with conditions. We should consider picking a sensible default value in order to improve the user experience of the driver.

I suggest changing the default to LOCAL_SERIAL, following the Rust Driver reasoning in the related PR:

This series adds a default serial consistency level for queries - LocalSerial. The decision is based on the fact that LocalSerial is the one that provides acceptable performance. Users interested in strong, cross-dc consistency - which could also cause prohibitive latencies - should override to Serial.