Revert "Add command func for abstract shell surface to get zindex"

This reverts commit aa5b9151d9f5d7229694924ac3269feb0bac4b4c.
Revert "Add command func for abstract shell surface to set zindex"

This reverts commit e9b13093848611d165fe652627948d46d2e3eaf2.
Rewrite z index member