remove sandbox

we haven't used this in five years. we set up sandbox once but never
actually had any concrete uses for spinning up an entire extra infra
setup outside the main deploy pipeline. none of these buckets exist and
no doubt the AWS infra is significantly out of date too.

app/config.py

@@ -546,21 +546,6 @@ class CloudFoundryConfig(Config):
     pass
 
 
-# CloudFoundry sandbox
-class Sandbox(CloudFoundryConfig):
-    NOTIFY_EMAIL_DOMAIN = 'notify.works'
-    NOTIFY_ENVIRONMENT = 'sandbox'
-    CSV_UPLOAD_BUCKET_NAME = 'cf-sandbox-notifications-csv-upload'
-    CONTACT_LIST_BUCKET_NAME = 'cf-sandbox-contact-list'
-    LETTERS_PDF_BUCKET_NAME = 'cf-sandbox-letters-pdf'
-    TEST_LETTERS_BUCKET_NAME = 'cf-sandbox-test-letters'
-    DVLA_RESPONSE_BUCKET_NAME = 'notify.works-ftp'
-    LETTERS_PDF_BUCKET_NAME = 'cf-sandbox-letters-pdf'
-    LETTERS_SCAN_BUCKET_NAME = 'cf-sandbox-letters-scan'
-    INVALID_PDF_BUCKET_NAME = 'cf-sandbox-letters-invalid-pdf'
-    FROM_NUMBER = 'sandbox'
-
-
 configs = {
     'development': Development,
     'test': Test,
@@ -568,5 +553,4 @@ configs = {
     'production': Live,
     'staging': Staging,
     'preview': Preview,
-    'sandbox': Sandbox
 }