- update tag to latest dendrite release (https://github.com/matrix-org/dendrite/releases/tag/v0.10.6)

- update to v0.10.1 (https://github.com/matrix-org/dendrite/releases/tag/v0.10.1)

- update to 0.10.0 (https://github.com/matrix-org/dendrite/releases/tag/v0.10.0)

- 0.9.9 (https://github.com/matrix-org/dendrite/releases/tag/v0.9.9)

Remove appservice database setup/config as the latest update no longer requires it.

* appservice: add and use matrix_homeserver_* vars

* appservice: use the new vars

* Apply suggestions from code review

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

Co-authored-by: Slavi Pantaleev <slavi@devture.com>

Looks like we've skipped a bunch of 0.8.x versions (up to 0.8.9)
and are jumping straight to 0.9.0.

This is untested. Judging by Dendrite's changelog, it shouldn't cause
any breakage though: https://github.com/matrix-org/dendrite/blob/v0.9.0/CHANGES.md

We're trying to move away from implementation-specific variables,
hoping for a clean (implementation-neutral) examples/vars.yml file.

Doing this seems more reasonable and simpler.

This brings dendrite.yaml up to date and cleans things up a bit.

We refrain from logging to files for all components,
because we rely on systemd-journald anyway.