MB-68157: Correct warmup_behavior upgrade

A recent change broke upgrade of bucket configs when attempting to
upgrade the warmup_behavior. This is now corrected.

Change-Id: I3354b8aa7a355e474308119c5e9d9b9a38309f7f
Reviewed-on: https://review.couchbase.org/c/ns_server/+/232543
Tested-by: Build Bot <[email protected]>
Reviewed-by: Neelima Premsankar <[email protected]>
Reviewed-by: Ben Huddleston <[email protected]>
Tested-by: Steve Watanabe <[email protected]>

Author: stevewatanabe

apps/ns_server/src/ns_bucket.erl

@@ -2899,7 +2899,7 @@ chronicle_upgrade_bucket_props_to_79(BucketName, ChronicleTxn) ->
                  {memory_high_watermark,
                   attribute_default(memory_high_watermark)},
                  {warmup_behavior,
-                  attribute_default(attribute_default)},
+                  attribute_default(warmup_behavior)},
                  {durability_impossible_fallback,
                   attribute_default(durability_impossible_fallback)},
                  %% The default value isn't used for existing buckets as it