t1300: write test expectations in the test's body

There are a bunch of tests in t1300 where we write the test expectation
handed over to `test_cmp ()` outside of the test body. This does not
match our modern test style, and there isn't really a reason why this
would need to happen outside of the test bodies.

Convert those to instead do so as part of the test itself. While at it,
normalize these tests to use `<<\EOF` for those that don't use variable
expansion and `<<-EOF` for those that aren't sensitive to indentation.

Note that there are two exceptions that we leave as-is for now since
they are reused across tests.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t