Disable Session Time Limits on existing hosts

When enabling Session Time Limits on a host pool, we have the option to apply this to existing hosts. However when disabling this, there is no option to apply to existing hosts. This means we are required to reimage or identify the configuration and apply it ourselves outside of Nerdio, which isn't ideal.

Any configuration that can optionally be applied to virtual machines via Nerdio should also be removable via Nerdio, without requiring a reimage (if technically possible).