chore: update Camunda Modeler screenshots to v5.19

[philippfromme]

Description

Related to camunda/camunda-modeler#4027

When should this change go live?

• This change is not yet live and should not be merged until {ADD_DATE} (apply hold label or convert to draft PR)?
• There is no urgency with this change.
• This change or page is part of a marketing blog, conference talk, or something else on a schedule.
• This functionality is already available but undocumented.
• This is a bug fix or security concern.

PR Checklist

• I have added changes to the relevant /versioned_docs directory, or they are not for an already released version.
• I have added changes to the main /docs directory (aka /next/), or they are not for future versions.
• My changes require an Engineering review, and I've assigned an engineering manager or tech lead as a reviewer, or my changes do not require an Engineering review.
• My changes require a technical writer review, and I've assigned @christinaausley as a reviewer, or my changes do not require a technical writer review.

[akeller]

Merge when you are ready @philippfromme and work with @christinaausley to coordinate a docs release so we can get these changes live!

[philippfromme]

Thanks, I will go ahead and merge. These changes can go live since the new Desktop Modeler has already been released.

[christinaausley]

Cool, I'll get a release out this morning!