Fix script entrypoint to correctly redirect stdout/stderr

[mzmssg]

This is full yarn entrypoint:
exec /bin/bash -c "source YarnContainerScripts/2.sh 1>$LAUNCHER_LOG_DIR/stdout 2>$LAUNCHER_LOG_DIR/stderr"
source will extract the exit_handler to parent process and bypass the redirect.

There are 2 fix options:

1. replace source with bash
2. move redirect out of quotation

Source:

Bash:

[coveralls]

Coverage remained the same at 52.932% when pulling 66c5009 on zimiao/fix_script_launcher into 5b3f044 on master.

[coveralls]

Coverage remained the same at 52.932% when pulling 66c5009 on zimiao/fix_script_launcher into 5b3f044 on master.

[coveralls]

Coverage remained the same at 52.932% when pulling 66c5009 on zimiao/fix_script_launcher into 5b3f044 on master.