lib: Handle metadata changes for send-only folders (fixes #4616, fixes #4627) (#4750)

Unignored files are marked as conflicting while scanning, which is then resolved
in the subsequent pull. Automatically reconciles needed items on send-only
folders, if they do not actually differ except for internal metadata.

lib/db/leveldb_dbinstance.go

@@ -324,7 +324,7 @@ func (db *Instance) availability(folder, file []byte) []protocol.DeviceID {
 	return devices
 }
 
-func (db *Instance) withNeed(folder, device []byte, truncate bool, needAllInvalid bool, fn Iterator) {
+func (db *Instance) withNeed(folder, device []byte, truncate bool, fn Iterator) {
 	t := db.newReadOnlyTransaction()
 	defer t.close()
 
@@ -351,12 +351,6 @@ func (db *Instance) withNeed(folder, device []byte, truncate bool, needAllInvali
 			if bytes.Equal(v.Device, device) {
 				have = true
 				haveFileVersion = v
-				// We need invalid files regardless of version when
-				// ignore patterns changed
-				if v.Invalid && needAllInvalid {
-					need = true
-					break
-				}
 				// XXX: This marks Concurrent (i.e. conflicting) changes as
 				// needs. Maybe we should do that, but it needs special
 				// handling in the puller.