Relax an eager sled agent assert - #10401

control: job assigned to worker 01M5DJBBC3BK1W91SVJVZZKGB7 [factory aws, i-0567078b07171b534] (queued for 46 s)
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task: starting task 0: "setup"
task: process exited: duration 4186 ms, exit code 0
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task: starting task 1: "rust-toolchain"
task: process exited: duration 17675 ms, exit code 0
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task: starting task 2: "authentication"
task: process exited: duration 17 ms, exit code 0
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task: starting task 3: "clone repository"
task: process exited: duration 12089 ms, exit code 0
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task: starting task 4: "build"
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| info: running `cargo check --bins` on zone-setup (371/371)
| warning: profile package spec `blake2b_simd` in profile `dev` did not match any packages
| warning: profile package spec `rust-argon2` in profile `dev` did not match any packages
|     Checking uzers v0.12.2
|     Checking zone-setup v0.1.0 (/work/oxidecomputer/omicron/zone-setup)
|     Finished `dev` profile [unoptimized + debuginfo] target(s) in 1.52s
| 
| real    12:20.101506395
| user    19:33.303197088
| sys      4:10.469735086
| trap        0.333573105
| tflt        0.790432227
| dflt        0.896568884
| kflt        0.003834721
| lock  1:00:06.103882322
| slp   1:32:02.486537919
| lat        42.661541372
| stop     3:24.602359969
task: process exited: duration 880751 ms, exit code 0
|W| found 0 output files