Bug 13431 [QA Follow-up]: Shared FastMmap file causes issues

Bug 13431 [QA Follow-up]: Shared FastMmap file causes issues

1) Removed 'use C4::Context;' because it can lead to introduction
of circular reference in the near future
2) Put fastmmap initialization code into an eval {} block, to catch
various kinds of errors which can still occur during it's init in
some [less usual] Koha setups and/or more unusual circumstances
3) Do not include UID in the sharefile name (it will be constructed
using namespace + database name + database host instead).

Test plan addendum:

   s/and UID//

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>