Bug 19683: Fix authority types in tools/export template

Bug 19683: Fix authority types in tools/export template

Fixes the bug by correcting the variable names in the template.

To test:
1) Tools > Export > Export authority records
2) Authority Types dropdown is not empty

Signed-off-by: Claire Gravely <claire.gravely@bsz-bw.de>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Amended: Changing the export script and unblessing is not needed.

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>