Remove 3PID binding during registration

This disables 3PID binding at registration time, so users won't be discoverable
by 3PID by default. Instead, new discovery controls in settings allow you to
opt-in.

Fixes https://github.com/vector-im/riot-web/issues/10424

src/components/structures/auth/Registration.js

@@ -403,14 +403,9 @@ module.exports = React.createClass({
         // clicking the email link.
         let inhibitLogin = Boolean(this.state.formVals.email);
 
-        // Only send the bind params if we're sending username / pw params
+        // Only send inhibitLogin if we're sending username / pw params
         // (Since we need to send no params at all to use the ones saved in the
         // session).
-        const bindThreepids = this.state.formVals.password ? {
-            email: true,
-            msisdn: true,
-        } : {};
-        // Likewise inhibitLogin
         if (!this.state.formVals.password) inhibitLogin = null;
 
         return this.state.matrixClient.register(
@@ -418,7 +413,7 @@ module.exports = React.createClass({
             this.state.formVals.password,
             undefined, // session id: included in the auth dict already
             auth,
-            bindThreepids,
+            null,
             null,
             inhibitLogin,
         );