fix: increase cache size for scanned images

Double the cache size for tracking images already scanned. Would allow images to be scanned less often since they can stay longer in the cache.

Author: ivanstanev

config.default.json

@@ -4,7 +4,7 @@
     "level": "info"
   },
   "IMAGES_SCANNED_CACHE": {
-    "MAX_SIZE": 10000,
+    "MAX_SIZE": 20000,
     "MAX_AGE_MS": 86400000
   },
   "WORKLOADS_SCANNED_CACHE": {