Add more information from the messages (requests took too long) parsed from etcd logs.

The advanced metrics are available on insights but OPCT does not use it by default. This stat can help to quickly review the existing etcd performance from the must-gather logs. The text file is already available for a quickly check by the reviewer on the path 

Goal:

• Add metrics like median, p99, max, etc parsed from the etcd logs of slow requests
• Update the documentation for v0.5 explaining this values: https://redhat-openshift-ecosystem.github.io/provider-certification-tool/user-installation-review/#review-disk-performance-with-etcd-fio 

Nice to have:

• stat by node, although it can be achieved in post-check using bash:

$ for POD_DIR in $(ls -d ${MUST_GATHER_PATH}/*/namespaces/openshift-etcd/pods/etcd-* |grep -v guard); do ETCD_POD=$(basename $POD_DIR); echo -en "\n\n#> $ETCD_POD\n"; cat ${MUST_GATHER_PATH}/*/namespaces/openshift-etcd/pods/$ETCD_POD/etcd/etcd/logs/current.log | ~/bin/ocp-etcd-log-filters ; done 

ENGINEERING REFERENCE:

It was useful on the investigation working in progress in SPLAT-1059.