[utils] Use in OnDemandPagedList by default

Not using cache results in redundant network I/O due to downloading the same pages while using --playlist-items n-m

youtube_dl/utils.py

@@ -1933,7 +1933,7 @@ class PagedList(object):
 
 
 class OnDemandPagedList(PagedList):
-    def __init__(self, pagefunc, pagesize, use_cache=False):
+    def __init__(self, pagefunc, pagesize, use_cache=True):
         self._pagefunc = pagefunc
         self._pagesize = pagesize
         self._use_cache = use_cache