Bug 18219: Remove duplicated code in returns.tt

Bug 18219: Remove duplicated code in returns.tt

Removed lines of code that were duplicated in bug 16530.
Fixes alignment of a few lines of code surrounding duplication.

Modifies returns.tt

To test:
1) Check in items that are not checked out.
2) Note duplicated problem message (i.e. "Not checked out.")
3) Apply patch.
4) Repeat step 1.
5) Note the problem message is no longer duplicated.

Followed test plan, works as expected.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>