Update media regenerate tests to use 125x125 image size
Update media regenerate tests to use 125x125 image size

TwentySeventeen now includes a 100x100 image size, which breaks our
tests for a custom image size.

miya0001/wp-cli,gitlost/wp-cli,rodrigoprimo/wp-cli,rodrigoprimo/wp-cli,gitlost/wp-cli,aaemnnosttv/wp-cli,rodrigoprimo/wp-cli,2ndkauboy/wp-cli,miya0001/wp-cli,GaryJones/wp-cli,2ndkauboy/wp-cli,trepmal/wp-cli,miya0001/wp-cli,GaryJones/wp-cli,2ndkauboy/wp-cli,gitlost/wp-cli,trepmal/wp-cli,GaryJones/wp-cli,trepmal/wp-cli,aaemnnosttv/wp-cli,aaemnnosttv/wp-cli