Bug 19024 Fix some infelicities of phrasing in test messages

Bug 19024 Fix some infelicities of phrasing in test messages

The test messages were awkwardly phrased, re phrase them to
sound more natuaral. Patch is cosmetic (grammar) only

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 16c25a36988b47fb9fcbabd91fdace5f98f9caed)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>