Delete agricultural AEZs in `gcam_sector_tech.csv`?

Note from @pkyle in #255:

>Leaving this open, but just in looking at it I noticed that the string "AEZ" appears in the agricultural technologies of this table. My guess is that these rows aren't used, and I should have deleted them here but overlooked it. So @bpbond you might leave a todo indicating that we need to delete the AEZs.
