Fix timeframe extension for weeks view

What does this MR do?

This MR fixes a bug in timeframe auto-expand for weeks view in medium screen sizes. Feature that this MR requires was introduced in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/9018.

Screenshots

Below screenshot shows incorrect timeframe with window size being 1800x1000.

Before	After

Does this MR meet the acceptance criteria?

• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides

#7325 (closed)