Upstream: avoid holding a cache node with upgraded connections.
Upstream: avoid holding a cache node with upgraded connections.

Holding a cache node lock doesn't make sense as we can't use caching
anyway, and results in "ignore long locked inactive cache entry" alerts
if a node is locked for a long time.

The same is done for unbuffered connections, as they can be alive for
a long time as well.

hy0kl/nginx,hy0kl/nginx,hy0kl/nginx