STAB-838: mention temporal in connection error messages

[johnmastro]

STAB-848 reported that, if e.g. the temporal server isn't running, the client logs Error: TonicTransportError(tonic::transport::Error(Transport, ConnectError(ConnectError("tcp connect error", Os { code: 111, kind: ConnectionRefused, message: "Connection refused" })))) without explicitly saying what it's trying to connect to.

tracing through what happens here:

• temporal's sdk-core returns a ClinitInitError, which is an enum wrapping other errors, some of which wrap yet other errors
• in our rust layer, we log the error (this is the Error: TonicTransportError message users see) and then forward it on (but replacing the concrete error type with a string representation of it)
• in our haskell layer, we conditionally retry (based on the retry config - which is 15 in mwb's config/settings.yml), and then eventually throw a ClientConnectionError if the retries are exhausted

what this looks like for a user is:

i think simply prepending the error messages with Error connecting to Temporal server: is the simplest solution here

[linear]

STAB-848 Emit a more meaningful connection error than the `TonicTransportError` that the Rust core emits

[linear]

STAB-838 Switch Temporal in production to API keys