Allow to customize keys for timezone_data helper

What does this MR do?

Implements #290295 (closed)

Allow to pick different sets of attributes for TimeZoneHelper.timezone_data helper.

It doesn't implement "custom" format suggested in #290295 (closed) we can add it when and if we need it.

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
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• [-] Database guides
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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
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
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