fix: double header display in checkout

[SGrueber]

PR Type

[x] Bugfix [ ] Feature [ ] Code style update (formatting, local variables) [ ] Refactoring (no functional changes, no API changes) [ ] Build-related changes [ ] CI-related changes [ ] Documentation content changes [ ] Application / infrastructure changes [ ] Other:

What Is the Current Behavior?

If the user is on a checkout page and refreshes the browser (F5) he sees the header twice for a short time (due to an hydration issue)

Issue Number: Closes #

What Is the New Behavior?

The header is shown on once.

Does this PR Introduce a Breaking Change?

[ ] Yes [x] No

Other Information

AB#100906