Bug 1962220 - Only ask a user to set to default once per profile group. r=profiles-reviewers,mossop

Filed followup bug 1985130 to test the pref copying using marionette
once bug 1960964 lands.

Differential Revision: https://phabricator.services.mozilla.com/D262472

Author: jaredhirsch

browser/components/profiles/SelectableProfileService.sys.mjs

@@ -182,6 +182,7 @@ class SelectableProfileServiceClass extends EventEmitter {
     "app.shield.optoutstudies.enabled",
     "browser.crashReports.unsubmittedCheck.autoSubmit2",
     "browser.discovery.enabled",
+    "browser.shell.checkDefaultBrowser",
     "browser.urlbar.quicksuggest.dataCollection.enabled",
     "datareporting.healthreport.uploadEnabled",
     "datareporting.policy.currentPolicyVersion",