The connection timeout was 2 minutes and the keep-alive
timeout was 11 minutes. If a vector store node became unreachable, these
long timeouts caused significant delays before the system could recover,
negatively impacting high availability.
This change aligns both timeouts with the `request_timeout`
configuration, which defaults to 10 seconds. This allows for much
faster failure detection and recovery, ensuring that unresponsive nodes
are failed over from more quickly.
Move the response_content_to_sstring utility function from
vector_store_client.cc to utils.hh to enable reuse across
multiple files.
This refactoring prepares for the upcoming `client.cc` implementation
that will also need this functionality.
