Revert "Disable l10nupdate for the duration of CLDR 26 plural migration"

Migration period is now over.

This reverts commit 5b02e75232620d8050ada203ec36918ad74860af.

Change-Id: I184eecfd4f1de866d22736995f442cf14711fd41
Merge "Revert "Disable l10nupdate for the duration of CLDR 26 plural migration"" into production