`events_mgmt` fix the broken `ProviderService` `createOrUpdateProvider()`

[francoisledroff]

The Conflict http response handling and error decoding was weak and broke
we need to harden it and fix it.

[francoisledroff]

fix released as part of https://github.com/adobe/aio-lib-java/releases/tag/aio-lib-java-1.0.6