[RFD 621 2/n] switch to Tufaceous v2 in Wicket and Installinator

[iliana]

This replaces Tufaceous v1 with Tufaceous v2 in Wicket, Installinator, and a couple of other crates. Closes #10733.

This PR is independent of (but somewhat useless without) #10676.

Most of the diff is like-for-like replacement but I did do a minor refactor to Installinator that greatly simplifies the code for downloading all of the artifacts listed in the Installinator document.

I manually tested this on berlin using the following procedure:

• Merged in [RFD 621 1/n] releng: generate Tufaceous v2 repos #10676, ran cargo xtask releng, and copied both the generated repo.zip and repo-v2.zip to castle.
• Started with whatever bits were previously on there (recent main + some commits that didn't touch these paths), and ran a clean slate.
• Old Wicket, new Installinator: uploaded repo.zip to sled 16 and installed to sled 14.
• New Wicket, new Installinator, v1 repo: uploaded repo.zip to sled 14 and installed to sled 16.
• New Wicket, new Installinator, v2 repo: uploaded repo-v2.zip to 16 and installed to sleds 15 and 17.

This testing went well, and everything behaved as expected. However when I went to initialize the control plane I realized that the zone tarball names were wrong in the v2 repo. I fixed that and used Wicket to deploy the new repo-v2.zip to all of the sleds, and the control plane successfully came up.

[iliana]

On berlin, uploaded the (v1) repo to Nexus and ran oxide system update recovery-finish; Reconfigurator seems pleased:

{
  "components_by_release_version": {
    "21.0.0-0.local+git46fbd8adcfa": 87
  },
  "suspended": false,
  "target_release": {
    "time_requested": "2026-07-06T22:35:08.640751Z",
    "version": "21.0.0-0.local+git46fbd8adcfa"
  },
  "time_last_step_planned": "2026-07-06T22:38:15.024838Z"
}