Fix inconsistent wording about leaving current space/room

For rooms, we already say "Leave this room".

When viewing a Space page, we have both "Leave the space" and "Leave this room". The "Leave the space" VS "Leave this space" was bothering me, and the Space page should say "Leave this space" instead of "Leave this room".

src/qml/SpaceHomePage.qml

@@ -62,7 +62,7 @@ ColumnLayout {
                     onClicked: _private.createRoom(root.currentRoom.id)
                 }
                 QQC2.Button {
-                    text: i18nc("@button", "Leave the space")
+                    text: i18nc("@action:button", "Leave this space")
                     icon.name: "go-previous"
                     onClicked: RoomManager.leaveRoom(root.currentRoom)
                 }