Error message is too Windows specific when MDM profile type can't be determined

[jahzielv]

Fleet version: <!-- Copy this from the "My account" page in the Fleet UI, or run fleetctl --version -->

Web browser and operating system:

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💥  Actual behavior

When an MDM profile's target OS can't be determined, we return an error that is Windows specific:

Windows configuration profiles can only have <Replace> or <Add> top level elements.

🧑‍💻  Steps to reproduce

1. Create a MacOS profile
2. Remove the first 2 lines from the profile
3. Attempt to upload the profile via fleetctl
4. Note the error that comes back

🕯️ More info (optional)

Was brought up while working on #16335.

For more context see Slack thread.

[noahtalerman]

I’m in favor of updating the validation to assume .mobileconfig is macOS only and .xml is Windows only.

[sharon-fdm]

@georgekarrv should this be on MDM board?

[lukeheath]

@georgekarrv @jahzielv It Looks like this bug was missed; please prioritize when possible since it's old.

[fleet-release]

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