[fix] container: remove static path mount (#5006)

I've seen that by default Granian sets a `Cache-Control` header for 1 day IF `GRANIAN_STATIC_PATH_MOUNT` is set. This option is not a hard requirement, but it's set because I found to be faster when serving the static files.

Another thing is that by removing `GRANIAN_STATIC_PATH_MOUNT`, the headers set by the application are present again in the static files, which was not the case before.

Related https://github.com/searxng/searxng/pull/5004

container/Dockerfile

@@ -51,8 +51,7 @@ ENV SEARXNG_VERSION="$SEARXNG_GIT_VERSION" \
     GRANIAN_LOOP="uvloop" \
     GRANIAN_BLOCKING_THREADS="4" \
     GRANIAN_WORKERS_KILL_TIMEOUT="30" \
-    GRANIAN_BLOCKING_THREADS_IDLE_TIMEOUT="300" \
-    GRANIAN_STATIC_PATH_MOUNT="/usr/local/searxng/searx/static/"
+    GRANIAN_BLOCKING_THREADS_IDLE_TIMEOUT="300"
 
 VOLUME $CONFIG_PATH
 VOLUME $DATA_PATH