If the configuration variable ``metadata_workers`` is not set,
the default value for ML2/OVN mechanism driver will be zero.
This value defines the number of separate workers that will
be spawned by the OVN metadata agent. By default, the OVN
metadata proxy handler will be executed inside the same OVN
metadata agent process, in a parallel thread. That reduces the
number of OVN SB database connections to one.
Related-Bug: #1993181
Change-Id: I8bc4f2784ccefe6078506bc27cc7a98c48192ad2
70a2029ca1