Also get rid of `--tags=update-user-password` in the
`matrix-dendrite` role, as what we had doesn't work.
We may be able to do it with some Ansible helper or something else.
For now, we'll omit this feature.
All the `matrix_s3_*` stuff happens in the `matrix-synapse` role.
If we are to have such S3 support for Dendrite, we should probably
extract it out of the `matrix-synapse` role (into a `matrix-s3` role or
`matrix-goofys`, etc.) and wire `matrix-dendrite` accordingly.
This may or may not be done in the future though. For now, I'm
cleaning things up in the `matrix-dendrite` role.
