vrrp: force sleeps between timer events

vrrp: force sleeps between timer events

Adding a virtual MAC to some NICs can take a significant amount of time.
If a lot of VRs enter the master state around the same time, the process
node can stay active for a very long time processing all of the transitions.

Try to force a 10 us sleep between processing events to ensure that the
process node does not prevent API messages and RPCs from being handled for
an extended period.

Type: improvement

Signed-off-by: Matthew Smith <[email protected]>
Change-Id: I400a7d395b4c0fec371f70d359e9d184ae79645e
(cherry picked from commit b41167a0bbbd3d81a2dd8e756d938f89b5ace5f3)