Update Appservice Discord 1.0.0 -> 3.0.0

Ref: https://github.com/matrix-org/matrix-appservice-discord/pull/826

```
docker pull ghcr.io/matrix-org/matrix-appservice-discord:v3.0.0
v3.0.0: Pulling from matrix-org/matrix-appservice-discord
751ef25978b2: Pull complete 
16af4ec8b188: Pull complete 
8c8f56f7dc53: Pull complete 
afa016f2f989: Pull complete 
683e2bbbda4e: Pull complete 
fb056adbb1d6: Pull complete 
716f59a72dc7: Pull complete 
d52c94fc1da3: Pull complete 
b7b9cd5ddbeb: Pull complete 
Digest: sha256:1009697517bfe07a0d2192cf3b982bc2dbe40829cedc82c100aef61f8a43e3de
Status: Downloaded newer image for ghcr.io/matrix-org/matrix-appservice-discord:v3.0.0
ghcr.io/matrix-org/matrix-appservice-discord:v3.0.0
```

roles/matrix-bridge-appservice-discord/defaults/main.yml

@@ -2,10 +2,12 @@
 # matrix-appservice-discord is a Matrix <-> Discord bridge
 # Project source code URL: https://github.com/Half-Shot/matrix-appservice-discord
 
-matrix_appservice_discord_enabled: true
+matrix_appservice_discord_enabled: false
+matrix_appservice_discord_container_image_self_build: false
 
-matrix_appservice_discord_version: v1.0.0
-matrix_appservice_discord_docker_image: "{{ matrix_container_global_registry_prefix }}halfshot/matrix-appservice-discord:{{ matrix_appservice_discord_version }}"
+matrix_appservice_discord_version: v3.0.0
+matrix_appservice_discord_docker_image: "{{ matrix_appservice_discord_docker_image_name_prefix }}matrix-org/matrix-appservice-discord:{{ matrix_appservice_discord_version }}"
+matrix_appservice_discord_docker_image_name_prefix: "{{ 'localhost/' if matrix_appservice_discord_container_image_self_build else 'ghcr.io' }}"
 matrix_appservice_discord_docker_image_force_pull: "{{ matrix_appservice_discord_docker_image.endswith(':latest') }}"
 
 matrix_appservice_discord_base_path: "{{ matrix_base_data_path }}/appservice-discord"