If multiple instances of a service are co-located on the same node then
their proxies will all share a cache entry for their resolved service
configuration. This is because the cache key contains the name of the
watched service but does not take into account the ID of the watching
proxies.
This means that there will be multiple agent service manager watches
that can wake up on the same cache update. These watchers then
concurrently modify the value in the cache when merging the resolved
config into the local proxy definitions.
To avoid this concurrent map write we will only delete the key from
opaque config in the local proxy definition after the merge, rather
than from the cached value before the merge.
