Bug 32586: Reindent items with no checkouts report template

Bug 32586: Reindent items with no checkouts report template

The indentation in the template was off and also full of tab
characters, so this does some clean-up prior to doing some
other small changes on separate bugs.

To test:
* Run the 'Items with no checkouts' report in the report module
* Note: If you get an error in this step, you need to turn of
  sql_strict_mode in your koha-conf.xml, but this bug is out
  of scope here.
* Apply patch
* Rerun the report, it should appear unchanged

Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
  → Nice to the eyes, and no regression
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>