[FEATURE] Improve telemetry error handling

[Kavindu-Dodan]

Requirements

Consider this conversation - #1188 (comment)

In the current implementation, errors in telemetry at the startup phase result in startup failure. While this has benefits, telemetry can be considered as non-critical sub-system and allow flagd/flagd-proxy to startup with warnings.

AC

Revisit configuration and startup logic. Migrate from fail fast to log and continue for telemetry errors.