MMAP tests seem to consistently fail on Windows CI now

[KristofferC]

Error During Test at C:\buildkite-agent\builds\win2k22-amdci6-5\julialang\julia-master\julia-0ffdf4eff0\share\julia\stdlib\v1.13\Mmap\test\runtests.jl:346
--
  | Got exception outside of a @test
  | IOError: unlink("C:\\Users\\julia\\AppData\\Local\\Temp\\jl_lGPoT0X2Ly"): permission denied (EACCES)
  | Stacktrace:
  | [1] _uv_error(prefix::String, c::Int32)
  | @ Base .\libuv.jl:114
  | [2] uv_error
  | @ .\libuv.jl:113 [inlined]
  | [3] unlink(p::String)
  | @ Base.Filesystem .\file.jl:1194
  | [4] rm(path::String; force::Bool, recursive::Bool, allow_delayed_delete::Bool)
  | @ Base.Filesystem .\file.jl:285
  | [5] rm(path::String)
  | @ Base.Filesystem .\file.jl:281
  | [6] top-level scope
  | @ C:\buildkite-agent\builds\win2k22-amdci6-5\julialang\julia-master\julia-0ffdf4eff0\share\julia\stdlib\v1.13\Mmap\test\runtests.jl:347
  | [7] macro expansion
  | @ C:\buildkite-agent\builds\win2k22-amdci6-5\julialang\julia-master\julia-0ffdf4eff0\share\julia\stdlib\v1.13\Test\src\Test.jl:1858 [inlined]
  | [8] macro expansion
  | @ C:\buildkite-agent\builds\win2k22-amdci6-5\julialang\julia-master\julia-0ffdf4eff0\share\julia\stdlib\v1.13\Mmap\test\runtests.jl:356 [inlined]
  | [9] include(mod::Module, _path::String)

[IanButterworth]

Note to self, or anyone else who might wonder why this doesn't show up on the buildkite flaky test monitoring.. The test reports currently have a limitation that they only upload the results from the first test agent attempt, and because our windows agents are so unreliable at starting tests a lot of windows test results aren't getting uploaded.

[adienes]

maybe related: #58736