fix(RHINENG-10369): fix merge/replace facts returns

[FabriciaDinizRH]

Overview

This PR is being created to address RHINENG-10369.
PATCH /hosts/{id}/facts/{namespace} and PUT /hosts/{id}/facts/{namespace} now returns 404 when given a non-existent hostname or namespace.

PR Checklist

• Keep PR title short, ideally under 72 characters
• Descriptive comments provided in complex code blocks
• Include raw query examples in the PR description, if adding/modifying SQL query
• Tests: validate optimal/expected output
• Tests: validate exceptions and failure scenarios
• Tests: edge cases
• Recovers or fails gracefully during potential resource outages (e.g. DB, Kafka)
• Uses type hinting, if convenient
• Documentation, if this PR changes the way other services interact with host inventory
• Links to related PRs

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Secure Coding Checklist

• Input Validation
• Output Encoding
• Authentication and Password Management
• Session Management
• Access Control
• Cryptographic Practices
• Error Handling and Logging
• Data Protection
• Communication Security
• System Configuration
• Database Security
• File Management
• Memory Management
• General Coding Practices

[kruai]

Clean, LGTM

[thearifismail]

LGTM

[kruai]

/retest

[FabriciaDinizRH]

/retest