feat: improve Redis container performance

- Disable RDB persistence (--save "") since Redis is used as a pure
  cache and lock store; snapshotting causes fork/CoW pressure and I/O spikes
- Set --maxmemory-policy allkeys-lru to enable LRU eviction and prevent
  unbounded memory growth
- Enable lazyfree background deletions (--lazyfree-lazy-*) to move key
  eviction, expiry, and DEL operations off the main event loop thread
- Enable active memory defragmentation (--activedefrag yes) for long-running
  instances
- Increase background task frequency to --hz 15 for faster key expiry
- Add Transparent Huge Pages (THP) startup warning, consistent with the
  existing vm.overcommit_memory check
- Refactor start.sh to build arguments via a bash array, avoiding eval
  and safely handling the empty-string --save "" and the password argument
- Remove the pre-existing unreachable exec "$@" at the end of start.sh
- Add timeout and read_timeout (1.5s) to standalone Redis config in
  redis.config.php to prevent PHP workers from hanging indefinitely

Agent-Logs-Url: https://github.com/nextcloud/all-in-one/sessions/e68c1986-419f-49b4-9cd0-c1f0efda0351
Co-Authored-By: Simon L. <szaimen@e.mail.de>
Co-Authored-By: szaimen <42591237+szaimen@users.noreply.github.com>

Containers/nextcloud/config/redis.config.php

@@ -7,6 +7,8 @@ if (getenv('REDIS_MODE') !== 'rediscluster') {
 
   if (getenv('REDIS_HOST')) {
     $CONFIG['redis']['host'] = (string) getenv('REDIS_HOST');
+    $CONFIG['redis']['timeout'] = 1.5;
+    $CONFIG['redis']['read_timeout'] = 1.5;
   }
 
   if (getenv('REDIS_HOST_PASSWORD')) {