Demote delete errors when distributor is enabled

Since delete errors for Tasks is expected after recovery (when another
nodes starts up) when running with a multi-primary setup, demote them to
"atFine()" level when the distributor is enabled. This avoids errors in
the logs during normal multi-primary operation.

Release-Notes: Reduced log level for Task deletion errors in MP setups
Change-Id: Iccca2e1bd2b91b91e12a14c4e473c8a6df6fd4b7