Delete unused SendGrid mock.

packages/server/__mocks__/@sendgrid/mail.ts

@@ -1,23 +0,0 @@
-// eslint-disable-next-line @typescript-eslint/no-unused-vars
-module SendgridMock {
-  class Email {
-    constructor() {
-      // @ts-ignore
-      this.apiKey = null
-    }
-
-    setApiKey(apiKey: any) {
-      // @ts-ignore
-      this.apiKey = apiKey
-    }
-
-    async send(msg: any) {
-      if (msg.to === "invalid@example.com") {
-        throw "Invalid"
-      }
-      return msg
-    }
-  }
-
-  module.exports = new Email()
-}