[Pinot Connector] Enable pinot grpc by default

[xiangfu0]

Pinot side has by default turn on grpc query endpoint, so it makes sense to turn on grpc endpoint by default as well.

Note that this won't impact existing users who don't turn on grpc, the fallback behavior to netty query endpoint happens automatically.

== RELEASE NOTES ==

Pinot Changes
* Prefer querying Pinot server grpc endpoint by default (through config `pinot.use-streaming-for-segment-queries`).

[xiangfu0]

cc: @highker