refactor(pingcap/tidb): rename `merged-build` job name to `merged-tidb-build` (#4031)the prow's `badge.svg` api only support `jobs` query param, so let'sadjust the job name that we can use the `badge.svg` api. (commit: f775cc6)
![[Jenkins]](/jenkins/static/16f78cb3/images/svgs/logo.svg){kind=logo}
