Fixesspring-projects/spring-integration#2213
JIRA: https://jira.spring.io/browse/INT-4123
Fully different `MessageStore`s can be configured for the same shared
Key-Value data-base.
Since the retrieval logic is based on the keys, that may cause the
unexpected messages expiration via `MessageGroupStoreReaper`.
* To distinguish store instances on the shared store add `prefix`
option to the `AbstractKeyValueMessageStore`
* Deprecate the `GemfireMessageStore` `Cache`-based configuration - `setIgnoreJta()` and `afterPropertiesSet()`.
The `GemfireMessageStore` relies only on an externally configured `Region`.
**Cherry-pick to 4.3.x**
Doc Polishing