Add the second part of the multirack join service - #10989

control: job assigned to worker 01M0ED2BPGSCSRRAY55D45MZBB [factory aws, i-02e72ea8951bc7dae] (queued for 52 s)
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task: starting task 0: "setup"
task: process exited: duration 4090 ms, exit code 0
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task: starting task 1: "rust-toolchain"
task: process exited: duration 16375 ms, exit code 0
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task: starting task 2: "authentication"
task: process exited: duration 18 ms, exit code 0
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task: starting task 3: "clone repository"
task: process exited: duration 11568 ms, exit code 0
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task: starting task 4: "build"
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| a out/probe.tar.gz 3037K
| a out/propolis-server.tar.gz 34642K
| a out/pumpkind-gz.tar 26647K
| a out/switch-softnpu.tar.gz 497962K
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| real     1:29.139904178
| user     1:26.142387494
| sys         5.007499165
| trap        0.006716027
| tflt        0.000000000
| dflt        0.000000000
| kflt        0.000000000
| lock        0.000000000
| slp      1:26.018898454
| lat         1.099837885
| stop        0.000165470
task: process exited: duration 1031285 ms, exit code 0
|W| found 1 output files
|W| uploading: /work/package.tar.gz (2758537744 bytes)
|W| uploaded: /work/package.tar.gz