18.9-RC4

Changes compared to: 18.9-RC3

Non user facing:

• Removes an unreleased feature that would cause a reload upon finishing the First-time Configuration in order to refresh form data and implements an alternative. #18419
• Hides the installation success page for old users upgrading into 18.9 #18417
• Shows a confirmation modal pup-up when the user tries to switch tab and there are unsaved changes in the current step #18407
• Updates links in the FTC SEO data optimization step #18418
• Fixes the placement of the Skip anchor in mobile view #18411
• Fixes an unreleased bug where error feedback in the social profiles step and social accounts tab would be misplaced upon deletion of another input. #18415
• Disables the usage tracking step in the FTC when it's not allowed at network level #18420