Revert "feat: set nginx log level by environment variable"

This reverts commit 450ae4d42d.

# Conflicts:
#	src/env.main

src/default.conf

@@ -1,4 +1,4 @@
-error_log /dev/stdout $JASIMA_LOG_LEVEL;
+error_log /dev/stdout;
 
 lua_shared_dict jasima_cache 20m;
 lua_package_path "/opt/sitelen-tu/?.lua;;";

src/env.main

@@ -1,3 +1,2 @@
-env JASIMA_LOG_LEVEL;
 env JASIMA_MATOMO_HOST;
 env JASIMA_PROXY_HOST;