Remove default keys, these are now specified in values.yaml

Specifically, the default keys in questions.yaml are ignored by the
frontend, even when set, and have no effect. I'm assuming these are
a holdover from some older version of the frontend.

packages/rancher-alerting/rancher-alerting-drivers/charts/questions.yml

@@ -3,17 +3,14 @@ categories:
 namespace: cattle-monitoring-system
 questions:
   - variable: prom2teams.enabled
-    default: false
     label: Enable Microsoft Teams
     type: boolean
     group: "General"
   - variable: sachet.enabled
-    default: false
     label: Enable SMS
     type: boolean
     group: "General"
   - variable: global.cattle.psp.enabled
-    default: "false"
     description: "Flag to enable or disable the installation of PodSecurityPolicies by this chart in the target cluster. If the cluster is running Kubernetes 1.25+, you must update this value to false."
     label: "Enable PodSecurityPolicies"
     type: boolean