tep-1007: Rename Metadata's `metadataItems` to `items`

Signed-off-by: 35V LG84 <35vlg84-x4e6b92@e257.fi>
2 jobs for tep/tep-1007-txn-set-checksum in 4 minutes and 49 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #166645885
test·jdk11

00:04:49

passed #166645886
test·jdk8

00:04:40

99.77%