Remove Visibility from terraform widget

What does this MR do?

The terraform widget was setup following other polling examples in the codebase, using Visibility.

Visibility seems to make unintended polling requests.

For example, when I click away from a screen (maybe to another tab on my browser) and click back a new poll request will generate. This will appear as a reload to the customer, even though they did not reload the page.

I did a bit more research and discovered Visibility is not required for polling, so I've removed it from the file.

Conformity

• Changelog entry
• Documentation (if required)
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• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

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• Label as security and @ mention @gitlab-com/gl-security/appsec
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