Correctly mention previous copyright (#16820)

During the migration the automated script to update the copyright
headers accidentally got rid of some of the existing copyright lines.
Reinstate them.

scripts-dev/check_locked_deps_have_sdists.py

@@ -2,6 +2,7 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2022 The Matrix.org Foundation C.I.C.
 # Copyright (C) 2023 New Vector, Ltd
 #
 # This program is free software: you can redistribute it and/or modify

scripts-dev/check_pydantic_models.py

@@ -2,6 +2,7 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2022 The Matrix.org Foundation C.I.C.
 # Copyright (C) 2023 New Vector, Ltd
 #
 # This program is free software: you can redistribute it and/or modify

scripts-dev/federation_client.py

@@ -2,6 +2,7 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2015, 2016 OpenMarket Ltd
 # Copyright (C) 2023 New Vector, Ltd
 #
 # This program is free software: you can redistribute it and/or modify

scripts-dev/mypy_synapse_plugin.py

@@ -1,6 +1,7 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2020 The Matrix.org Foundation C.I.C.
 # Copyright (C) 2023 New Vector, Ltd
 #
 # This program is free software: you can redistribute it and/or modify

scripts-dev/release.py

@@ -2,6 +2,7 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2020 The Matrix.org Foundation C.I.C.
 # Copyright (C) 2023 New Vector, Ltd
 #
 # This program is free software: you can redistribute it and/or modify

scripts-dev/schema_versions.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python
 # Copyright 2023 The Matrix.org Foundation C.I.C.
+# Copyright 2023 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.

scripts-dev/sign_json.py

@@ -2,6 +2,7 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2020 The Matrix.org Foundation C.I.C.
 # Copyright (C) 2023 New Vector, Ltd
 #
 # This program is free software: you can redistribute it and/or modify