Bug 6254: (follow-up) work-around to fix a failing test case

Bug 6254: (follow-up) work-around to fix a failing test case

This patch ensures that a patron category that is present
in the (English) sample data is used for the ILS-DI tests,
avoiding a situation where one part of AddMember was trying
to access a patron category via DBIC but failed because
it was not visible to it yet.

Note that this will become easier once C4::Context->dbh
and DBIC are using the same base DBI database handles.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>