Remove govuk from possible brands

‘GOV.UK’ doesn’t make sense as a type of brand. It only made sense as
a type of branding that a service had.

Since we’ve:
- deprecated the service branding column
- made sure it’s not used as a value in the email branding table

we can remove this value from the table of possible brand types.

migrations/versions/0221_nullable_service_branding.py

@@ -4,6 +4,7 @@ Revises: 0220_email_brand_type_non_null
 Create Date: 2018-08-24 13:36:49.346156
  """
 from alembic import op
+from app.models import BRANDING_ORG, BRANDING_GOVUK
 
 
 revision = '0221_nullable_service_branding'
@@ -20,6 +21,22 @@ def upgrade():
     op.alter_column('services_history', 'branding', nullable=True)
     op.alter_column('services', 'branding', nullable=True)
 
+    op.execute("""
+        update
+            email_branding
+        set
+            brand_type = '{}'
+        where
+            brand_type = '{}'
+    """.format(BRANDING_ORG, BRANDING_GOVUK))
+
+    op.execute("""
+        delete from
+            branding_type
+        where
+            name = '{}'
+    """.format(BRANDING_GOVUK))
+
 
 def downgrade():
 
@@ -30,3 +47,11 @@ def downgrade():
 
     op.alter_column('services', 'branding', nullable=False)
     op.alter_column('services_history', 'branding', nullable=False)
+
+    op.execute("""
+        insert into
+            branding_type
+                (name)
+            values
+                ('{}')
+    """.format(BRANDING_GOVUK))