The `vector_store_client_uri_update_to_invalid` test was flaky because
it performed real DNS lookups, making it dependent on the network
environment.
This commit replaces the live DNS queries with a mock to make the test
hermetic and prevent intermittent failures.
`vector_search_metrics_test` test did not call configure{vs},
as a consequence the test did real DNS queries, which made the test
flaky.
The refreshes counter increment has been moved before the call to the resolver.
In tests, the resolver is mocked leading to lack of increments in production code.
Without this change, there is no way to test DNS counter increments.
The change also simplifies the test making it more readable.
ac5e9c34b6