Don't log JsonParseException in the gateway as errors

[remcowesterhoud]

Describe the bug

When a user sends a request containing variables (e.g. complete job) and these variables cannot be converted to MsgPack a JsonParseException. Currently these exceptions are logged with an error level by the gateway. This is unexpected, as the fault here lies with the user, who sends the wrong variables. We should add an exception to the GrpcErrorMapper#mapErrorToStatus method so we don't go into the default error logging flow.

To Reproduce

1. Create a process with a service task
2. Complete the job with invalid variables: {"test":123
3. Watch as the gateway logs an error

Expected behavior

No errors should be logged

Log/Stacktrace

Full Stacktrace

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Environment:

• OS: Cloud
• Zeebe Version: 8.0.4