demo-orgs: Set organization type to "unspecified".

Instead of having "business" as the default organization type
for demo organizations in the dev environment, we set it to
"unspecified". This way a more generic zulip guide email will
be sent as part of the onboarding process for users invited
to try out the demo organization if the owner has not yet
updated the organization type.

zerver/views/development/registration.py

@@ -92,7 +92,7 @@ def register_demo_development_realm(request: HttpRequest) -> HttpResponse:
     name = "Your name"
     email = ""
     realm_name = generate_demo_realm_name()
-    realm_type = Realm.ORG_TYPES["business"]["id"]
+    realm_type = Realm.ORG_TYPES["unspecified"]["id"]
     realm_subdomain = realm_name
     email_address_visibility = UserProfile.EMAIL_ADDRESS_VISIBILITY_NOBODY
     prereg_realm = create_preregistration_realm(email, realm_name, realm_subdomain, realm_type)