Lib: Acknowledge messages with Queue after storing them in DB

**Detailed Description**
Currently it's done the other way round.

**Actual Behavior**
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**Expected Behavior**
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**Environment:**
- Java: [e.g. OpenJDK 11.0.4]
- Node: [e.g. v12.9.1-x86]
- OS: [e.g. Ubuntu 18.04]
- Version: [e.g. 1.0.1]

**Additional Context**
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