Exclude cells from CPU utilisation monitor
Exclude cells from CPU utilisation monitor

The cells consistantly spike to relatively high levels of CPU due to
tennant behaviour which causes false positives and noise for support.
We are less concerned with high CPU on these instances so have decided
to remove them from the monitor.

We were also seeing both "critical" and "warning" level notifications at
the same time due to our split of "moderately high cpu over a long time"
and "high cpu over a short time". This doesn't add much value, so have
switched to using a single monitor with higher thresholds over a 1hr
period.

alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf