## What changes were proposed in this pull request?

Add a SPARK_NO_DAEMONIZE environment variable flag to spark-daemon.sh that causes the process it would run to be run in the foreground.

It looks like there has been some prior work in https://github.com/apache/spark/pull/3881, but there was some talk about these being refactored. I'm not sure if that happened or not, but that PR is almost 2 years old at this point so it was worth revisiting.

## How was this patch tested?

./dev/run-tests still seems to work. It doesn't look like these scripts have tests, but if I missed them just let me know.

Author: Mike Ihbe <mikejihbe@gmail.com>

Closes #15338 from mikejihbe/SPARK-11653.