Fix SetServiceInstances data race (#16367)
Fix SetServiceInstances data race (#16367)

A recent PR introduced a new call to SetServiceInstances that will
concurrently with another call. Since this isn't protected by a mutex
(and I think that is a good thing), this causes a data race.

In pushConnection we already call SetServiceInstances, so we don't need
to set them here as well, and removing this fixes the race.
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