Replaced email_recipient_filter with email_segment in admin-api-schema

refs https://github.com/TryGhost/Team/issues/1596
refs TryGhost/Ghost#14798

Also dropped send_email_when_published

Author: SimonBackx

packages/admin-api-schema/lib/schemas/posts.json

@@ -182,10 +182,7 @@
         "email": {
           "strip": true
         },
-        "send_email_when_published": {
-          "strip": true
-        },
-        "email_recipient_filter": {
+        "email_segment": {
           "strip": true
         },
         "frontmatter": {