fix(quick_actions/spend_time_and_date_separator): Check if timezone is empty string as well

• Please check this box if this contribution uses AI-generated content (including content generated by GitLab Duo features) as outlined in the GitLab DCO & CLA. As a benefit of being a GitLab Community Contributor, you receive complimentary access to GitLab Duo.

What does this MR do and why?

fix(quick_actions/spend_time_and_date_separator): Check if timezone is empty string as well

Before the condition to initialize the user profile timezone does only check if the value is nil. But the value could sometimes also be an empty string. So we need to check against that condition with .presence as well.

References

Issue