Prior to this commit, we were relying on the
`"spring.main.cloud-platform"` property for overriding cloud platform
detection and enabling liveness and readiness probes. Changes made in
gh-20553 have now been reverted.

This commit adds the `"management.health.probes.enabled"` configuration
property. The auto-configuration now enables the HTTP Probes and
`HealthIndicator` if this property is enabled, or if the Kubernetes
cloud platform is detected.

This property is `false` by default for now, since enabling this for all
Spring Boot applications would be a breaking change. In this case, the
global `"/actuator/health"` endpoint could report `OUT_OF_SERVICE`
during startup time because the application now reports the readiness as
well.

See gh-19593