Revert part of 6207399
Revert part of 6207399

older sqlite doesn't support indexes on expressions, lets just
store things lowercase in the db

TribeMedia/synapse,TribeMedia/synapse,matrix-org/synapse,TribeMedia/synapse,matrix-org/synapse,matrix-org/synapse,matrix-org/synapse,matrix-org/synapse,matrix-org/synapse,TribeMedia/synapse,TribeMedia/synapse