Disable 'Fleet Commander' 'session_provider' in runtime if server side doesn't have corresponding LDAP schema

[alexey-tikhonov]

This is to avoid unnecessary traffic for a vast majority of sssd-ipa users without touching default value.

See #7119 (comment)

Technically, you can identify this feature by presence of its LDAP schema. This is something easily discoverable but would require storing something in a domain struct, probably. https://github.com/abbra/freeipa-desktop-profile/blob/master/plugin/schema.d/75-deskprofile.ldif
I am worried about existing deployments. These tend to be not a single PC style ones, so updating deployed systems is a bit hard.
Changing the code to only query whether the scheme is present at domain online check would achieve pretty much the same but would reduce LDAP traffic as you wanted.