[llvm] [CI] Extend metrics container to log BuildKite metrics (PR #129699)

[Nathan Gauër via llvm-commits]

Keenuts wrote:

Turns out the issue I had was due to the way we kept track of the last visited workflow.
But It seems it was overly complex for no reason: the workflows are returned sorted, and we can even filter the 'completed' ones at the query level.
Meaning we only need to keep track of one workflow ID: the one we checked.
Logic is not similar to the buildkite version.

https://github.com/llvm/llvm-project/pull/129699