Apply T306747 to wmf wikis
# **ALTERs to run:** https://gerrit.wikimedia.org/r/c/mediawiki/extensions/GlobalBlocking/+/785376/1/sql/mysql/patch-globalblocks-timestamps.sql
# **Where to run those changes:** centralauth database only
# **When to run those changes:** any time
# **If the schema change is backwards compatible:** Yes
# **If the schema change has been tested already on some of the test/beta wikis:** beta cluster is running with the new schema
# **if the data should be made available on the labs replicas and/or dumps:** no change of the existing rules
This makes `gb_timestamp` a fixed length column and removes default of empty string from `gb_expiry`
Progress
[x] dbstore1008
[x] db2220
[x] db2218 master
[x] db2208
[x] db2200
[x] db2198
[x] db2187
[x] db2182
[x] db2168
[x] db2159
[x] db2150
[x] db2122
[x] db2121
[x] db2098
[] db1236 master
[x] db1227
[x] db1202
[x] db1194
[x] db1191
[x] db1181
[x] db1174
[x] db1171
[x] db1170
[x] db1158 sanitarium master
[x] db1155
[x] clouddb1021
[x] clouddb1018
[x] clouddb1014