eslint-config-wikimedia version 0.20.0 included a commit that disabled the one-var rule by default[1][2]. Repos that use that version or newer no longer need to manually disable the rule, and such disables can be removed.
[1] tagging of 0.20.0 including changelog entry "Allow var blocks to be split and moved" https://github.com/wikimedia/eslint-config-wikimedia/commit/4ff99ae786e66a1efce0b5f6b090af6303fceee3
[2] the commit for that entry which removes the one-var entry https://github.com/wikimedia/eslint-config-wikimedia/commit/b90a3665c9ee0c024a8d76677d65ba7e766c030d