refactor: use InternalHasAuthority() for internal self-calls in NetworkObject

[noellie-velez]

Purpose of this PR

• Replaced HasAuthority property accesses inside NetworkObject with direct InternalHasAuthority() calls
• Rephrased two inline comments, changed !transform.parent to transform.parent == null, and fixed a doc comment to use

Jira ticket

MTT-14792

Changelog

N/A

Documentation

• No documentation changes or additions were necessary.

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Functional Testing

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• Manual testing done

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• Execute manual tests?
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Backports

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