nixos/tests/quake3: Don't quote +set arguments

With the new upstream Git version of ioquake3 introduced in 7fc7502d

, the
arguments to the quake3(server) binaries/wrappers may no longer be
passed as full single arguments (like "+set foo bar") but rather as
separate arguments (like "+set" "foo" "bar"), otherwise they will be
completely ignored.

Ran the x86_64-linux test on my machine and it now succeeds.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>