bunnynet_pullzone.devxy-r-binaries (cran.devxy.io) and
bunnynet_pullzone.cran_rpkgs_com (cran.rpkgs.com) were byte-for-byte
identical except for the zone name and hostname. Same for the two
pullzone_hostname resources.
Use a single local.pullzones map and for_each on both resources, so
shared knobs (block_ips, limit_bandwidth, s3_auth_*, ...) only have
to be edited once.
State migration is handled by moved {} blocks so the existing
pullzones get re-addressed under the new for_each keys instead of
being destroyed+recreated. Run terraform plan to confirm a zero-
change apply before applying.
