Add database migration to update L2C subscription descriptions to the new format

gso/migrations/versions/2025-06-17_550e3aebc1c5_update_l2c_descriptions.py

+"""Update Layer 2 Circuit subscription descriptions.
+
+Revision ID: 550e3aebc1c5
+Revises: d23b59abc6a5
+Create Date: 2025-06-04 16:08:56.288635
+
+This database migration updates the description of all Layer2Circuit-type subscriptions by having fit the format:
+``product_name - custom_service_name``.
+"""
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = '550e3aebc1c5'
+down_revision = 'd23b59abc6a5'
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    conn = op.get_bind()
+    conn.execute(sa.text("""
+UPDATE subscriptions s
+SET    description = (
+           Regexp_replace(subscriptions.description, '^(.+) - .+$', '\\1 - ') || 
+           subscription_instance_values.value
+       )
+FROM   subscriptions
+       JOIN products
+         ON subscriptions.product_id = products.product_id
+       JOIN product_product_blocks
+         ON products.product_id = product_product_blocks.product_id
+       JOIN product_block_resource_types
+         ON product_product_blocks.product_block_id =
+            product_block_resource_types.product_block_id
+       JOIN resource_types
+         ON product_block_resource_types.resource_type_id =
+            resource_types.resource_type_id
+       JOIN subscription_instances
+         ON subscriptions.subscription_id =
+            subscription_instances.subscription_id
+       JOIN subscription_instance_values
+         ON ( resource_types.resource_type_id =
+              subscription_instance_values.resource_type_id
+              AND subscription_instances.subscription_instance_id =
+                  subscription_instance_values.subscription_instance_id )
+WHERE  resource_types.resource_type = 'custom_service_name'
+       AND products.product_type = 'Layer2Circuit'
+       AND s.subscription_id = subscriptions.subscription_id;
+    """))
+
+
+def downgrade() -> None:
+    pass