Bug 18652: Get rid of tt directive in translation for uncertainprice.tt

Bug 18652: Get rid of tt directive in translation for uncertainprice.tt

Translation tool shows toe following for ncertainprice.tt
0; url=[% scriptname %]?booksellerid=[% booksellerid %]

This patch fixes it.

To test:
- Apply patch
- Verify that code change makes sense
- Verify that Home > Acquisitions > [vendor] > Uncertain prices for [vendor]
  works as before

- Additional test (for a langunage 'aa-AA')
  perl translate create aa-AA
  verify that line 41 no longer appears in aa-AA-staff-prog.po

Amended to switch from BLOCK to a template variable, see comment #5

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 2ee82801c7a8686523f9c5e95b0f43d44e52e4ab)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>