Change default parameters for better mean-time-to-recovery (MTTR)

[lfrancke]

HBase has a few knobs that can be turned to improve the time it takes to recover from failure.

These are documented here:

• https://hbase.apache.org/book.html#mttr
• https://issues.apache.org/jira/browse/HBASE-21186
• https://github.com/apache/ambari/blob/1fb531c31e86688d5d3a696d4ad6d07921d99aa1/ambari-server/src/main/resources/stacks/BIGTOP/3.2.0/services/HBASE/configuration/hbase-site.xml#L4

As part of this issue we need to check whether all of these parameters still exist, whether they are still needed and whether the values suggested still make sense.

If not we should also contribute documentation fixes upstream.