t3302: coding style updates

Use "<<-END_OF_HERE_TEXT" to push the contents of here-text to the
right in order to show the loop structure better.

Use write_script when writing a script to be run.

Use "test" (not "[ ... ]") and avoid unnecessary ";" in the middle
of a line.

Signed-off-by: Junio C Hamano <gitster@pobox.com>