The tabGroups.onRemoved / onCreated / onMoved event depends on the
isAdoptingGroup / removedByAdoption flags to identify tab groups that are
adopted by another window. Although this flag is set for the
`gBrowser.adoptTabGroup` method, it is not in the
`gBrowser.replaceGroupWithWindow` method, which results in incorrect
events.
This patch fixes the issue by setting the isAdoptingGroup flag in
`gBrowser.replaceGroupWithWindow`.
Differential Revision: https://phabricator.services.mozilla.com/D248327
e7af560fb9