Create separate implementations for MessageStore and MessageGroupStore [INT-2673]

[spring-operator]

Gunnar Hillert opened INT-2673 and commented

Ultimately we might be able to provide a simpler more focussed implementation for the various use-cases (Aggregator versus Claim Check)

This may also lead to a simpler table setup for supporting plain MessageStore implementations e.g. used by Claim Check. This should help improving Scalability of Claim Check

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This issue is a sub-task of #6647