chore: mark native image checks as required (#697)

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Fixes #<issue_number_goes_here> ☕️

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java-os-login/.github/sync-repo-settings.yaml

@@ -16,6 +16,8 @@ branchProtectionRules:
       - 'Kokoro - Test: Integration'
       - cla/google
       - OwlBot Post Processor
+      - 'Kokoro - Test: Java GraalVM Native Image'
+      - 'Kokoro - Test: Java 17 GraalVM Native Image'
   - pattern: java7
     isAdminEnforced: true
     requiredApprovingReviewCount: 1