AUTO: Explicitly include FIRETEXT_URL in manifest

- We are explicit about MMG_URL but not FIRETEXT_URL
- credentials has already been updated (checked by doing make
  generate-manifest for all envs)

manifest.yml.j2

@@ -84,6 +84,7 @@ applications:
       MMG_INBOUND_SMS_AUTH: '{{ MMG_INBOUND_SMS_AUTH | tojson }}'
       MMG_INBOUND_SMS_USERNAME: '{{ MMG_INBOUND_SMS_USERNAME | tojson }}'
 
+      FIRETEXT_URL: '{{ FIRETEXT_URL }}'
       FIRETEXT_API_KEY: '{{ FIRETEXT_API_KEY }}'
       LOADTESTING_API_KEY: '{{ LOADTESTING_API_KEY }}'
       FIRETEXT_INBOUND_SMS_AUTH: '{{ FIRETEXT_INBOUND_SMS_AUTH | tojson }}'