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.

Source: 12f420ab95/mautrix_twitter/example-config.yaml

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' {} +