write_prometheus: don't use AI_ADDRCONFIG for resolving bind address

write_prometheus: don't use AI_ADDRCONFIG for resolving bind address

Fixes #4150

write_prometheus uses getaddrinfo to resolve the bind address.
The AI_ADDRCONFIG flag causes getaddrinfo to refuse to resolve
0.0.0.0 when the system has no non-loopback IPv4 addresses configured
and refuse to resolve :: when the system has no non-loopback IPv6 configured.

We want binding to a wildcard address (0.0.0.0 or ::) to always work,
even if the network is down.

To achieve that, don't pass the AI_ADDRCONFIG flag
when resolving a bind address.