Bug 23385: Hide 'Default values' fields by default

Bug 23385: Hide 'Default values' fields by default

To test:
1 - Go to Tools->Import patrons
2 - Choose a file
3 - Scroll a long way to submit
4 - Apply patch
5 - Choose a file
6 - Can submit easily
7 - Click to expand and enter default fields
8 - Confirm can still submit and that values entered are used

Signed-off-by: Maryse Simard <maryse.simard@inlibro.com>
Signed-off-by: George Williams <george@nekls.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit 9258d385baa94a00f671dea6315c7738a8f38026)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>