Remove spring-boot-starter-cloud-connectors

[scottfrederick]

spring-boot-starter-cloud-connectors was deprecated in Spring Boot 2.2.0. We should consider removing it in 2.3.0.

[wilkinsona]

+1 for removing it in 2.3.

[philwebb]

Lets do it. We can even try to get it into M1 if there's time.