Demote rename errors when distributor is enabled

Since rename errors for Tasks is common and normal when running with a
multi-primary setup, demote them to "atFine()" level when the
distributor is enabled. This avoids making the logs extrememly noisy
during normal multi-primary operation.

Change-Id: I0c90aff769b12f5a1a7506a92f11358c34457cb1