Agent injector config not compatible with bao executable

[eremincho]

Describe the bug
The Config struct in config.go marshalls the Openbao key as openbao, but the agent command in the bao executable, expects the key to be vault.

To Reproduce
Steps to reproduce the behavior:

1. Deploy application annotated for openbao-agent injection
2. The openbao agent init sidecar will fail because the config file is incorrect

Expected behavior
Consistent naming between applications

Additional context
I guess openbao trying to maintain compatibility with vault-k8s for the moment, but how is this change going to be reconciled? At the moment we are patching openbao-k8s to fix this issue. Is there any planned change to either repo to fix this? Looking at the main openbao repo I don't see any issue referencing this.