Update segment-io namespace to use application's not monitoring's

[zdtsw]

From testing :

 Changing this setting from the dashboard "cluster settings" page appears to work fine, but in the backend I see no changes to the odh-segment-key configmap.
configmap/secret from segment is now stored in the monitoring namespace instead of the applications namespace.

This PR is to change namespace where segment-io CM is created.
cherry-pick : opendatahub-io#433

fix: opendatahub-io#445

[etirelli]

lgtm