Add arm64 support for rust-synapse-compress-state by switching container image

This switches the playbook from devture/rust-synapse-compress-state (a
container image which wraps the upstream-prebuilt amd64 binary of
rust-synapse-compress-state) to registry.gitlab.com/mb-saces/rust-synapse-compress-state
(https://gitlab.com/mb-saces/rust-synapse-compress-state), which builds
rust-synapse-compress-state from source and provides a multi-arch image
that currently works on amd64 and arm64.

Ideally, we'll stop using `:latest` and arm32 support will be made
available upstream as well at some point.
Discussed here: https://gitlab.com/mb-saces/rust-synapse-compress-state/-/issues/1

roles/matrix-synapse/defaults/main.yml

@@ -620,11 +620,11 @@ matrix_synapse_redaction_retention_period: 7d
 matrix_synapse_user_ips_max_age: 28d
 
 
-matrix_synapse_rust_synapse_compress_state_docker_image: "devture/rust-synapse-compress-state:v0.1.0"
+matrix_synapse_rust_synapse_compress_state_docker_image: "registry.gitlab.com/mb-saces/rust-synapse-compress-state:latest"
 matrix_synapse_rust_synapse_compress_state_docker_image_force_pull: "{{ matrix_synapse_rust_synapse_compress_state_docker_image.endswith(':latest') }}"
 
 matrix_synapse_rust_synapse_compress_state_base_path: "{{ matrix_base_data_path }}/rust-synapse-compress-state"
-matrix_synapse_rust_synapse_compress_state_synapse_compress_state_in_container_path: "/synapse-compress-state"
+matrix_synapse_rust_synapse_compress_state_synapse_compress_state_in_container_path: "/usr/local/bin/synapse_compress_state"
 
 
 # Default Synapse configuration template which covers the generic use case.