Remove welcome user from config

Until we update its tutorial videos to the current interface

electron_app/riot.im/config.json

@@ -13,7 +13,6 @@
     ],
     "hosting_signup_link": "https://modular.im/?utm_source=riot-web&utm_medium=web",
     "bug_report_endpoint_url": "https://riot.im/bugreports/submit",
-    "welcomeUserId": "@riot-bot:matrix.org",
     "roomDirectory": {
         "servers": [
             "matrix.org"

riot.im/app/config.json

@@ -14,7 +14,6 @@
     "bug_report_endpoint_url": "https://riot.im/bugreports/submit",
     "features": {
     },
-    "welcomeUserId": "@riot-bot:matrix.org",
     "piwik": {
         "url": "https://piwik.riot.im/",
         "siteId": 1,

riot.im/develop/config.json

@@ -27,7 +27,6 @@
         "feature_presence_in_room_list": "labs",
         "feature_custom_themes": "labs"
     },
-    "welcomeUserId": "@riot-bot:matrix.org",
     "piwik": {
         "url": "https://piwik.riot.im/",
         "siteId": 1,