os: TestRemoveAllWithMoreErrorThanReqSize is failing on Plan 9 and Windows [1.13 backport]

[gopherbot]

@dmitshur requested issue #35117 to be considered for backport to the next 1.13 minor release.

@gopherbot, please backport to Go 1.13. This is a test fix. It is needed to fix resolve a test failure in the os package on windows-amd64-longtest builder, which could be masking other problems (due to #36181) and making releasing Go 1.13.x more difficult.

[gopherbot]

Change https://golang.org/cl/223700 mentions this issue: [release-branch.go1.13] os: use an actual RemoveAll failure in TestRemoveAllWithMoreErrorThanReqSize

[gopherbot]

Closed by merging f353662 to release-branch.go1.13.