[HOTFIX] Fix PySpark pip packaging tests by non-ascii compatible character

## What changes were proposed in this pull request?

PIP installation requires to package bin scripts together.

https://github.com/apache/spark/blob/master/python/setup.py#L71

The recent fix introduced non-ascii compatible (non-breackable space I guess) at apache@ec96d34 fix.

This is usually not the problem but looks Jenkins's default encoding is `ascii` and during copying the script, there looks implicit conversion between bytes and strings - where the default encoding is used

https://github.com/pypa/setuptools/blob/v40.4.3/setuptools/command/develop.py#L185-L189

## How was this patch tested?

Jenkins

Closes apache#22782 from HyukjinKwon/pip-failure-fix.

Authored-by: hyukjinkwon <gurwls223@apache.org>
Signed-off-by: hyukjinkwon <gurwls223@apache.org>

Author: HyukjinKwon

bin/docker-image-tool.sh

@@ -79,7 +79,7 @@ function build {
   fi
 
   # Verify that Spark has actually been built/is a runnable distribution
-  # i.e. the Spark JARs that the Docker files will place into the image are present
+  # i.e. the Spark JARs that the Docker files will place into the image are present
   local TOTAL_JARS=$(ls $JARS/spark-* | wc -l)
   TOTAL_JARS=$(( $TOTAL_JARS ))
   if [ "${TOTAL_JARS}" -eq 0 ]; then