Add constraint for validation of deploy_access_levels

What does this MR do and why?

Part of Data integrity issue on `protected_environment_... (#330483 - closed),

• Validate ProtectedEnvironments::DeployAccessLev... (!114449 - merged) adds model validation
• Fix invalid protected environment access levels (!115549 - merged) fixes invalid records in the database
• this MR adds check constraint

blocked by !115549 (merged)

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