Protobuf not decoded and deserialized and passed to controller

### Task List

- [x] Steps to reproduce provided
- [na] Stacktrace (if present) provided
- [x] Example that reproduces the problem uploaded to Github
- [x] Full description of the issue provided (see below)

### Steps to Reproduce

1. Controller that receives a protobuf message
2. pass a APIGatewayProxyRequestEvent with a base64 encoded protobuf message to the MicronautLambdaContainerHandler
3. receive 400 with message "Required Body [] not specified"

Repo with test that replicates the behavior - https://github.com/KnutKnutson/proxy-proto-aws-gateway-micronaut/blob/main/app/src/test/kotlin/micronaut/proxy/proto/AppTest.kt#L61

### Expected Behaviour

The proper controller route should be found and executed with the decoded and deserialized proto message

### Actual Behaviour

receive 400 with message "Required Body [] not specified"

### Environment Information

- **Operating System**: mac os
- **Micronaut Version:** 2.5.1
- **JDK Version:** 11.0.11

### Example Application

- https://github.com/KnutKnutson/proxy-proto-aws-gateway-micronaut/blob/main/app/src/test/kotlin/micronaut/proxy/proto/AppTest.kt#L61

Start with the reproducing test in app/src/test/kotlin/micronaut/proxy/proto/AppTest.kt and trace how MicronautLambdaContainerHandler handles the APIGatewayProxyRequestEvent. Confirm the protobuf body is decoded and deserialized, then verify the proper controller route executes instead of returning the required-body 400 response.

Written by the indexing model from the issue text.