test: detach snapshots from component installation order

[rami3l]

Currently, quite a few of our test snapshots rely on the messages sent to our notification center similar to the following:

info: downloading component 'cargo'
info: downloading component 'rust-docs'
...
info: installing component 'cargo'
...

... however, the order will no longer be guaranteed once @FranciscoTGouveia makes these events concurrent, meaning there will be a different CLI output format which doesn't guarantee the order of such events.

This PR has made such snapshots agnostic to the specific forms of these message, and turn to other means such as rustup component list --installed if necessary.

Concerns

• Proper verification: verified in https://github.com/rust-lang/rustup/actions/runs/16726200278/job/47342369030?pr=4436.