fix(mastodon): Use basic redis protocol without redis

This patch removes some of the work that introduces sentinel as part of
the redis deployment. Sadly Mastodon isn't really sentinel compatible,
which makes it quite redundant. Instead we introduce a new service for
the redis-cluster, because the operator has this feature only in
unstable versions for now. This service will always point to the current
master node.

apps/base/mastodon/redis.yaml

 apiVersion: databases.spotahome.com/v1
 kind: RedisFailover
 metadata:
+  labels:
+      app.kubernetes.io/name: mastodon
   name: mastodon-redis
   namespace: mastodon
 spec:
@@ -22,3 +24,20 @@ spec:
       limits:
         memory: 256Mi
         cpu: 200m
+---
+apiVersion: v1
+kind: Service
+metadata:
+  labels:
+    app.kubernetes.io/name: mastodon
+  name: mastodon-redis-master
+  namespace: mastodon
+spec:
+  ports:
+  - name: redis
+    port: 6379
+    protocol: TCP
+    targetPort: 6379
+  selector:
+    app.kubernetes.io/name: mastodon-redis
+    redisfailovers-role: master
\ No newline at end of file

apps/base/mastodon/release.yaml

@@ -161,6 +161,6 @@ data:
       enabled: false
     redis:
       enabled: false
-      redisUrl: redis://rfs-mastodon-redis:26379/mymaster
+      redisUrl: redis://mastodon-redis-master:6379
       auth:
         enabled: false