modernize t9300: single-quote placement and indentation

Many test cases do not follow our modern style that places the
single-quotes that surround the shell code snippets before and after
the shell code. Make it so.

Many of the lines changed in this way are indented other than by a
single tab. Change them (and some additional lines) to be indented
with a tab.

Signed-off-by: Johannes Sixt <[email protected]>
Signed-off-by: Jeff King <[email protected]>

Author: j6t