[Code]: add ui.enabled flag and fix uneccessary usage of enabled flag

[zfy0701]

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• This was checked for cross-browser compatibility, including a check against IE11
• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
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• This was checked for breaking API changes and was labeled appropriately
• This includes a feature addition or change that requires a release note and was labeled appropriately

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request