Hard-code "enter" for adding lines in integration tests

This one doesn't make a difference in practice because we don't remap the key in
tests, but if we would, then this would no longer work correctly. It's just more
correct this way.

pkg/integration/components/commit_description_panel_driver.go

@@ -27,7 +27,7 @@ func (self *CommitDescriptionPanelDriver) SwitchToSummary() *CommitMessagePanelD
 }
 
 func (self *CommitDescriptionPanelDriver) AddNewline() *CommitDescriptionPanelDriver {
-	self.t.pressFast(self.t.keys.Universal.Confirm)
+	self.t.pressFast("<enter>")
 	return self
 }