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.

synapse/_scripts/export_signing_key.py

@@ -2,6 +2,7 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2019 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

synapse/_scripts/generate_log_config.py

@@ -3,6 +3,7 @@
 #
 # 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

synapse/_scripts/generate_signing_key.py

@@ -2,6 +2,7 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2019 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

synapse/_scripts/generate_workers_map.py

@@ -2,6 +2,7 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2022-2023 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

synapse/_scripts/register_new_matrix_user.py

@@ -1,6 +1,8 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2021-22 The Matrix.org Foundation C.I.C.
+# Copyright 2015, 2016 OpenMarket Ltd
 # Copyright (C) 2023 New Vector, Ltd
 #
 # This program is free software: you can redistribute it and/or modify

synapse/_scripts/review_recent_signups.py

@@ -1,6 +1,7 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2021 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

synapse/_scripts/synapse_port_db.py

@@ -2,6 +2,8 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2019 The Matrix.org Foundation C.I.C.
+# Copyright 2015, 2016 OpenMarket Ltd
 # Copyright (C) 2023 New Vector, Ltd
 #
 # This program is free software: you can redistribute it and/or modify

synapse/_scripts/synctl.py

@@ -2,6 +2,7 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2014-2016 OpenMarket Ltd
 # Copyright (C) 2023 New Vector, Ltd
 #
 # This program is free software: you can redistribute it and/or modify

synapse/_scripts/update_synapse_database.py

@@ -1,6 +1,7 @@
 #
 # This file is licensed under the Affero General Public License (AGPL) version 3.
 #
+# Copyright 2019 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