fixed display of available dictionaries strings

Since commit 9dc57be59d1a8dc17e77f21cbce04e2bb7247dca under
Tools->Options->LanguageSettings->WritingAids "User-defined
dictionaries" the language strings are displayed as
" '[' Language (Country) ']'"
that before was and instead should be
"[Language (Country)]"

Change-Id: Id7e7ef6ab86112c46707f1451a072dfc196aec44
(cherry picked from commit cc658066aec0a0f9589e7f9522c4431b3a3d5e96)
Reviewed-on: https://gerrit.libreoffice.org/8829
Tested-by: Michael Stahl <mstahl@redhat.com>
Reviewed-by: Michael Stahl <mstahl@redhat.com>