test-hashmap: remove 'hash' command

test-hashmap: remove 'hash' command

If hashes like strhash() are updated, for example to use a different
hash algorithm, we should not have to be updating t0011 to change out
the hashes.

As long as hashmap can store and retrieve values, and that it performs
well, we should not care what are the values of the hashes. Let's just
focus on the externally visible behavior instead.

Suggested-by: Jeff King <redacted>
Signed-off-by: Christian Couder <redacted>
Signed-off-by: Junio C Hamano <redacted>