Remove broken mysql example

examples/preflight/mysql.yaml

@@ -1,23 +0,0 @@
-apiVersion: troubleshoot.replicated.com/v1beta1
-kind: Preflight
-metadata:
-  name: sample
-spec:
-  collectors:
-    - mysql:
-        collectorName: my-mysql
-        uri: postgresql://doadmin:nokq949a9dom9qyx@postgres-test-do-user-1634526-0.a.db.ondigitalocean.com:25060/defaultdb?sslmode=require
-  analyzers:
-    - mysql:
-        checkName: Must be postgres 10.x or later
-        collectorName: pg
-        outcomes:
-          - fail:
-              when: "connected == false"
-              message: Cannot connect to postgres server
-          - fail:
-              when: "version < 10.x"
-              message: The postgres server must be at least version 10
-          - pass:
-              message: The postgres connection checks out
-