Bug 7034: de-nesting C4/Branch.pm

Bug 7034: de-nesting C4/Branch.pm

use C4::Koha was loaded only to call C4::Koha::get_infos_of in get_branchinfos_of

the sub get_branchinfos_of was used nowhere
(checked with "grep -R get_branchinfos_of *")
only one reference was made to get_branchinfos_of, in reserve/request.pl, but the sub was not used in fact (maybe removed previously & silently)

This patch removes sub get_branchinfos_of and use C4::Koha in C4::Branch, as well as the reference in request.pl and the t test

The patch doesn't remove use C4::Branch in reserve/request.pl, as it's still used for other subroutines.

Signed-off-by: Ian Walls <ian.walls@bywatersolutions.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>