This commit mainly fixes empty keys due to RDB loading and restore command,
which was omitted in #9297.
1) When loading quicklsit, if all the ziplists in the quicklist are empty, NULL will be returned.
If only some of the ziplists are empty, then we will skip the empty ziplists silently.
2) When loading hash zipmap, if zipmap is empty, sanitization check will fail.
3) When loading hash ziplist, if ziplist is empty, NULL will be returned.
4) Add RDB loading test with sanitize.
(cherry picked from commit cbda492909cd2fff25263913cd2e1f00bc48a541)
09c63c45dd