[mysql] metric metadata should be updated.

[truthbk]

The metric metadata is a bit outdated after the big overhaul six months ago, we should update it.

[l0k0ms]

This issue can be closed @masci @truthbk.

I have passed a fair amount of updates on metric metadata files since 6 months + now we have the support team that is reporting if there is a metrics metadata file that is outaded.

[masci]

Thanks!