Fix FXiOS-12300 [Tab Optimization] Only persist tab data after tabs have been removed#29911

Cramsden wants to merge 3 commits intomainmozilla-mobile/firefox-ios:mainfrom

cr/FXIOS-12300_fix-remove-tab-slownessmozilla-mobile/firefox-ios:cr/FXIOS-12300_fix-remove-tab-slownessCopy head branch name to clipboard