[Dashboard] [Reporting] Chrome no longer hidden for reports

[Heenawter]

Describe the bug:

When generating Dashboard reports in versions >= 8.16.0, the Kibana chrome is not hidden as it should be.

Steps to reproduce:

1. Open a sample Dashboard
2. Generate a print-optimized PDF report or add &_a=(viewMode:'print') to the end of you URL to simulate the print layout
3. Notice that the chrome shows up 🔥

Current behaviour:

ReportGeneratedOnMain.pdf:

ReportGeneratedOnV8.16.2.pdf:

Expected behaviour:

ReportGeneratedOnV8.15.5.pdf:

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)

[Heenawter]

This is an unintended consequence of this PR - specifically, the removal of the useEffect in src/plugins/dashboard/public/dashboard_top_nav/internal_dashboard_top_nav.tsx. Unfortunately, it is not as simple as simply adding this useEffect back because it was removed to fix a bug with fullscreen mode.

That being said, we could toggle the chrome visibility by subscribing to the viewMode publishing subject instead, perhaps? cc @nreese just in case this would have unintended consequences 🤔