Bug 23222: Update plugins-home.tt with new ENABLE/DISABLE flag name

Bug 23222: Update plugins-home.tt with new ENABLE/DISABLE flag name

At some point of history, the flag to indicate if a plugin was enabled/disabled was called "enabled", now it's called "is_enabled"

To test:
1) get a fresh master copy
2) Enable plugins
3) Install any plugin
CHECK => plugin appears as disabled
      => If you try to enable it, it just appears as disabled just the same
4) Apply this patch
5) Reload page
SUCCESS => plugin appears as enabled
        => enable / disable action works again
6) Sign off

Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>