Remove extra quotation marks.

Previously Genome::Sys->bsub_and_wait was putting this into ``s, so the
quotation marks were necessary.  Now it's using IPC::System::Simple, so
each string is already a single token in the array of parameters.

(This fix is similar to commit 2fa2de5dcd3b9cf470461c7124f7accfd35686a7dd)