t4205: indent here documents

Our usual style in the test scripts is to indent here
documents with tabs, and use "<<-" to strip the tabs. The
result is easier to read.

This old test script did not do so in its inception, and
further tests added onto it followed the local style. Let's
bring it in line with our usual style.

Some of the tests actually care quite a bit about
whitespace, but none of them do so at the beginning of the
line (because they use things like qz_to_tab_space to avoid
depending on the literal whitespace), so we can do a fairly
mechanical conversion.

Most of the here-docs also use interpolation, so they have
been left as "<<-EOF". In a few cases, though, where
interpolation was not in use, I've converted them to
"<<-\EOF" to match our usual "don't interpolate unless you
need to" style.

Signed-off-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>