[EE] Validate page after visit in block

What does this MR do?

When visit is called with a block it would execute the block first and then try to validate the initial page, event though the code in the block might have navigated to a different page.

It now visits the page before validating it, and then executes the block.

This fixes one of the problems associated with https://gitlab.com/gitlab-org/quality/nightly/issues/103 (which was causing geo tests to fail, after the other problems were fixed)

CE port: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/29524

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/62062

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content