Update CI label as the base image for mysql-9 now is 9.4

Both places fixed

Given this is label only changes and tests still pass and Andy confirmed we got all the places, I'm going to go out on a limb here and mark this RTBC. Feel free to kick it back.

Confirmed that neither of these are LTS releases, and this is just reflecting the status quo, so let's just change the label.

Committed/pushed to 11.x, thanks!

catch → closed merge request !12874