Bug 16502: Replace a few other ok-calls by is-calls

Bug 16502: Replace a few other ok-calls by is-calls

Trivial changes that speak for themselves..

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Srdjan <srdjan@catalyst.net.nz>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 8204024f1c21102c0649dec70d10398131aab953)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
(cherry picked from commit 2b7a9479b601e224ff6cdbdcc3162426a4727406)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>