Jenkins: Install extended read permission plugin

Extended read permission plugin allows everyone to view th job
configurations.

Task-number: QTQAINFRA-784
Change-Id: Ib3cce56b722c4f21eaa0e3731cfbbfe6621dae38
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>