Fix s3 api object list with params max-keys and prefix

[annluda]

What problem are we solving?

redis as filer store, suppose bucket have objects:

demo_v1
demo_v10
demo_v11
demo_v12
demo_v2
demo_v20

when request s3api list objects with params max-keys and prefix, like http://localhost:8333/test?max-keys=2&prefix=demo_v2, we got 0 result. Because the item's rank in redis is bigger than the max-keys.

How are we solving the problem?

drop isLastItemHasPrefix, compare the prefix and lastFileName directly.

How is the PR tested?

Checks

• I have added unit tests if possible.
• I will add related wiki document changes and link to this PR after merging.

[chrislusf]

Thanks for the fix! This part of code is tricky. Do you want to add some tests for this?