Unreviewed label is confusing and its timeline should improve

[elibarzilay]

In case where am owner approval was given but a maintainer approval is needed, the code sees that there is no approval and goes into the unreviewed timeline and the Unreviewed label is obviously confusing. See for example DefinitelyTyped/DefinitelyTyped#50161 (which I captured to test when this is fixed).

[jablko]

approverKind !== "maintainer" would fix this? https://github.com/DefinitelyTyped/dt-mergebot/pull/254#discussion_r537579951