Fix workspaces url_prefix field

- Fixes incorrect inclusion of protocol in
  db/migrate/20240106000000_migrate_data_from_workspaces_url_column.rb
- See https://gitlab.com/gitlab-com/gl-infra/production/-/issues/17459

Changelog: other
EE: true

db/migrate/20240106000000_migrate_data_from_workspaces_url_column.rb

@@ -13,7 +13,7 @@ def up
     each_batch_range('workspaces', scope: ->(table) { table.all }, of: BATCH_SIZE) do |min, max|
       execute(<<~SQL)
         UPDATE workspaces
-        SET url_prefix = CONCAT('https://#{DEFAULT_PORT}-', name),
+        SET url_prefix = CONCAT('#{DEFAULT_PORT}-', name),
             dns_zone = remote_development_agent_configs.dns_zone,
             url_query_string = CASE
                                     WHEN POSITION('?' IN url) > 0

db/migrate/20240123000000_update_workspaces_url_prefix_column.rb

+# frozen_string_literal: true
+
+class UpdateWorkspacesUrlPrefixColumn < Gitlab::Database::Migration[2.2]
+  milestone '16.8'
+  disable_ddl_transaction!
+
+  restrict_gitlab_migration gitlab_schema: :gitlab_main
+
+  def up
+    execute(<<~SQL)
+      UPDATE workspaces
+      SET url_prefix=REPLACE(url_prefix, 'https://', '')
+      WHERE url_prefix LIKE 'https://%'
+    SQL
+  end
+
+  def down
+    # no-op
+  end
+end

db/schema_migrations/20240123000000

+554281098ec89db0f0bc0402e34c1fe413003afa63b0001da8d5ad772dd9725c
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