[SPARK-3235][SQL] Ensure in-memory tables don't always broadcast.

Author: Michael Armbrust <michael@databricks.com>

Closes #2147 from marmbrus/inMemDefaultSize and squashes the following commits:

5390360 [Michael Armbrust] Merge remote-tracking branch 'origin/master' into inMemDefaultSize
14204d3 [Michael Armbrust] Set the context before creating SparkLogicalPlans.
8da4414 [Michael Armbrust] Make sure we throw errors when leaf nodes fail to provide statistcs
18ce029 [Michael Armbrust] Ensure in-memory tables don't always broadcast.