Rename lock statistics that have redundant or misleading text

As part of reviewing some statistics we noticed that the commit timestamp queue lock application thread time waiting for the dhandle lock statistic has a spurious for the dhandle lock text. This is due to a copy-paste error, that likely applies to other statistics as well (and the original statistic description wasn't enhanced by duplicating the lock name. We should update those statistics descriptions to be accurate and concise.

Related to WT-3894