`core` improve `FeignUtil` `BaseBuilder` to better tune resiliency

[nicdard]

Improve resiliency in FeignUtil BaseBuilder:

• tune retries (either using the Retryer support provided by Feign or using resiliency4j integration)
• follow up: maybe add other resiliency patterns

Some resources:

• https://www.baeldung.com/feign-retry
• https://resilience4j.readme.io/docs/feign