Fix SPARK_EXECUTOR_JAVA_OPTS assignment bug

env | grep SPARK_JAVA_OPT_ |...

This is susceptible to a few bugs particularly around newlines in values. I see two ways around it.
ensuring the matching name is at the start, -E '^SPARK_JAVA_OPT_', and running all the commands with null-terminated input and output: env -0 and -z on the other commands
or bash variable prefix expansion

for v in "${!SPARK_JAVA_OPT_@}"; do
SPARK_EXECUTOR_JAVA_OPTS+=( "${!v}" )
done