[CI] Rename teamcity messages testMeta to testMetadata

Summary:
The Teamcity message for uploading arbitrary test values is
testMetadata and not testMeta. This should make the values be
displayed in the Teamcity UI.

Test Plan:

../contrib/teamcity/build-configurations.py build-bench

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D9229