Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1682

Previously, when matrix-postgres was disabled, we were setting
`matrix_mautrix_twitter_database_engine` to an invalid empty value.

Now, we always hardcode `matrix_mautrix_twitter_database_engine: postgres`,
but set/unset the database hostname and password values instead.

Signed-off-by: Aaron Raimist <aaron@raim.ist>

Remove references to sqlite since we should just use postgres from the
outset.

Updates based off the variable names used in mautrix-facebook role.

Also update port number in defauts/main.yml, and disable presence
checking, because Twitter doesn't support that.

find roles/matrix-bridge-mautrix-twitter -type f -exec sed -i \
  -e 's/facebook/twitter/g' \
  -e 's/Facebook/Twitter/g' \
  -e 's/FB/Twitter/g' \
  -e 's/fb/twitter/g' {} +