Move DS's Kerberos env vars to unit file

The IPA specific env vars KRB5_KTNAME and KRB5CCNAME are now defined in
a instance specific ipa-env.conf unit file.

Fixes: https://pagure.io/freeipa/issue/7860
Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>

ipaserver/install/krbinstance.py

@@ -386,10 +386,6 @@ class KrbInstance(service.Service):
 
         self.fstore.backup_file(paths.DS_KEYTAB)
         installutils.create_keytab(paths.DS_KEYTAB, ldap_principal)
-
-        vardict = {"KRB5_KTNAME": paths.DS_KEYTAB}
-        ipautil.config_replace_variables(paths.SYSCONFIG_DIRSRV,
-                                         replacevars=vardict)
         pent = pwd.getpwnam(constants.DS_USER)
         os.chown(paths.DS_KEYTAB, pent.pw_uid, pent.pw_gid)