Rename `HTTP_REQUEST_RETRIES` to `ANN_RETRIES` in `vector_store_client`,
as it now applies to all vector store nodes, not just HTTP requests.
Also, remove an unused test setter function.
The DNS resolution logic now processes all IP addresses returned in a DNS
response, not just the primary one.
The client will iterate through the list of resolved IPs, attempting to
query the next one if a request fails. This improves high availability
by allowing the client to query other available nodes if one is down.
The DNS resolution logic and its background task are moved out of the
`vector_store_client` and into a new, dedicated class `vector_search::dns`.
This refactoring is the first step towards supporting DNS hostnames
that resolve to multiple IP addresses.
Signed-off-by: Karol Nowacki <karol.nowacki@scylladb.com>
Vector search related implementation moved to a new module vector_search.
As the vector search functionality is going to be extended, it is
better to keep it in a separate module.
