fix(data): Use /data for persisting files and file caches (#295)

Moves sentry-data volume to /data mount point and sets all file-based storage settings to /data/files, /data/dsym-cache etc. accordingly. See 50ac550666/src/sentry/options/defaults.py (L45-L54)

sentry/config.example.yml

@@ -55,7 +55,9 @@ system.secret-key: '!!changeme!!'
 
 filestore.backend: 'filesystem'
 filestore.options:
-  location: '/var/lib/sentry/files'
+  location: '/data/files'
+dsym.cache-path: '/data/dsym-cache'
+releasefile.cache-path: '/data/releasefile-cache'
 
 # filestore.backend: 's3'
 # filestore.options: