Disable MySQL iowaits and tablelocks collection
    
    These metrics were found to be of very high cardinality, consuming
    lots of space in the TSDB.
    Disabling the collection since we do not currently have a use for
    them in manual queries, and they are not part of any alerting rules
    or dashboards.
    
    Signed-off-by: Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>