warmup_min_items_threshold is not honored under metadata eviction policy

Steps to reproduce:
1)Configure bucket with value eviction policy and set warmup_min_items_threshold to 10% using ns_server's REST api.
2)Restart the node for warmup and observe below stats:
curr_items_tot:99999
ep_warmup_value_count:10004
3)change the eviction policy to metadata eviction, the bucket warmup runs again
the stats are now as follows:
curr_items_tot:99999
ep_warmup_value_count:99999

complete warmup stats for second warmup:
ep_warmup: enabled
ep_warmup_dups: 0
ep_warmup_estimate_time: 54464
ep_warmup_estimated_key_count: 99999
ep_warmup_estimated_value_count: 0
ep_warmup_item_expired: 0
ep_warmup_key_count: 99999
ep_warmup_keys_time: 101946
ep_warmup_min_item_threshold: 10
ep_warmup_min_memory_threshold: 100
ep_warmup_oom: 0
ep_warmup_state: done
ep_warmup_thread: complete
ep_warmup_time: 357686
ep_warmup_value_count: 99999