[SPARK-3709] Executors don't always report broadcast block removal properly back to the driver

The problem was that the 2nd argument in RemoveBroadcast is not tellMaster! It is "removeFromDriver". Basically when removeFromDriver is not true, we don't report broadcast block removal back to the driver, and then other executors mistakenly think that the executor would still have the block, and try to fetch from it.

cc @tdas

Author: Reynold Xin <rxin@apache.org>

Closes #2588 from rxin/debug and squashes the following commits:

6dab2e3 [Reynold Xin] Don't log random messages.
f430686 [Reynold Xin] Always report broadcast removal back to master.
2a13f70 [Reynold Xin] iii
[SPARK-3734] DriverRunner should not read SPARK_HOME from submitter's environment

When using spark-submit in `cluster` mode to submit a job to a Spark Standalone
cluster, if the JAVA_HOME environment variable was set on the submitting
machine then DriverRunner would attempt to use the submitter's JAVA_HOME to
launch the driver process (instead of the worker's JAVA_HOME), causing the
driver to fail unless the submitter and worker had the same Java location.

This commit fixes this by reading JAVA_HOME from sys.env instead of
command.environment.

Author: Josh Rosen <joshrosen@apache.org>

Closes #2586 from JoshRosen/SPARK-3734 and squashes the following commits:

e9513d9 [Josh Rosen] [SPARK-3734] DriverRunner should not read SPARK_HOME from submitter's environment.