Treat as Error not Warning non-YAML #cloud-config user-data

Cloud-init 22.4.2

Currently when user-data is of type #cloud-config YAML, cloud-init only emits a WARNING message.

2022-12-16 22:55:13,550 - util.py[DEBUG]: Attempting to load yaml from string of length 127 with allowed root types (<class 'dict'>,)
2022-12-16 22:55:13,551 - util.py[WARNING]: Failed loading yaml blob. Invalid format at line 5 column 26: "while scanning an alias
  in "<unicode string>", line 5, column 26:
      interactive-sections: [*]
                             ^
expected alphabetic or numeric character, but found ']'
  in "<unicode string>", line 5, column 27:
      interactive-sections: [*]

I proposed that specific known user-data types like #cloud-config that are not able to be processed because of invalid format should be treated as an error because:
 * #cloud-config is a known YAML format and something that isn't YAML parseable represents a that needs immediate attention
 * #cloud-config was intended configuration on the system, ignoring that confiration exposes the system to long-running misconfiguration or security flaws
 * warnings do not result in discoverable error conditions or exit codes from cloud-init system service status
 * warnings do not bubble up to `cloud-init status --long`

                              ^"