VMM/serviceset: Fixed a conditional ProgrammingError. Affects only setups with Dovecot < v1.2.beta2. Actually the SQL query in method ServiceSet._load_by_services wasn't updated. Removed unnecessary code, which would have also produced a ProgrammingError, if it would have been correct.

# use glob syntax.
syntax: glob

*~
*.py?
.*.swp
.swp
build
debian/vmm
debian/*.log
debian/*.debhelper
debian/files
debian/*substvars
.pc
*.egg-info