Make sure Hazelcast bootstraps before any JCache setup

This commit makes sure that if a `javax.cache.CacheManager` is required,
an auto-configured `HazelcastInstance` is fully resolved first. This
prevents the case where the JCache bootstrap actually starts an instance
early, followed by a second (potentially unwanted) instance created by the
regular auto-configuration.

Since the JCache implementation works with an `HazelcastInstance` behind
the scenes, if there is one `HazelcastInstance` configured and it has a
name, then we configure the `CacheProvider` to use that. Future Hazelcast
version will allow to pass the instance directly (i.e. not requiring an
actual name).

Closes gh-8484

spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -3984,6 +3984,10 @@ NOTE: Since a cache library may offer both a native implementation and JSR-107 s
 Spring Boot will prefer the JSR-107 support so that the same features are available if
 you switch to a different JSR-107 implementation.
 
+TIP: Spring Boot has a <<boot-features-hazelcast,general support for Hazelcast>>t. If
+a single `HazelcastInstance` is available, it is automatically reused for the
+`CacheManager` as well unless the `spring.cache.jcache.config` property is specified.
+
 There are several ways to customize the underlying `javax.cache.cacheManager`:
 
 * Caches can be created on startup via the `spring.cache.cache-names` property. If a