modernize t9300: mark here-doc words to ignore tab indentation

In the next commit, we will indent test case preparations. This will
require that here-documents ignore the tab indentation. Prepare for
this change by marking the here-doc words accordingly. This does not
have an effect now, but will remove some noise from the git diff -b
output of the next commit.

The change here is entirely automated with this perl command:

  perl -i -lpe 's/(cat.*<<) *((EOF|(EXPECT|INPUT)_END).*$)/$1-$2 &&/' t/t9300-fast-import.sh

i.e., inserts a dash between << and the EOF word (and removes blanks
that our style guide abhors) and appends the && that will become
necessary.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Jeff King <peff@peff.net>