This enables the dynamic generation of the list of rules files for
prometheus, driven by the rules added in the appropriate tree under
.Values.conf.prometheus.rules. This removes the necessity of adding
the file name manually in addition to defining the rules in the
rules tree, which should reduce overhead associated with adding
new rules for prometheus to evaluate
Change-Id: Ib768a252c5ea4f2d099df534c3ffcfb2949d7481
616c351fa7