[v2] flaky test TestCmdSiteDelete_ValidateInput/kubernetes_flags_are_not_valid_on_this_platform

[c-kruse]

Describe the bug
Observed this test failing in CircleCI: https://app.circleci.com/pipelines/github/skupperproject/skupper/4581/workflows/fedb06f2-1b8e-44fd-ae90-d21de862d94b/jobs/29968/parallel-runs/0/steps/0-107

=== RUN   TestCmdSiteDelete_ValidateInput
File written to /home/circleci/.local/share/skupper/namespaces/test/input/resources/site/my-site.yaml
=== RUN   TestCmdSiteDelete_ValidateInput/site_name_is_not_specified
=== RUN   TestCmdSiteDelete_ValidateInput/site_name_is_not_specified,_all
=== RUN   TestCmdSiteDelete_ValidateInput/site_name_is_nil
=== RUN   TestCmdSiteDelete_ValidateInput/site_name_is_not_valid
=== RUN   TestCmdSiteDelete_ValidateInput/more_than_one_argument_is_specified
=== RUN   TestCmdSiteDelete_ValidateInput/site_doesn't_exist
=== RUN   TestCmdSiteDelete_ValidateInput/kubernetes_flags_are_not_valid_on_this_platform
Warning: --context flag is not supported on this platform
Warning: --kubeconfig flag is not supported on this platform
    validate_input.go:17: assertion failed: error is not nil: site my-site does not exist
--- FAIL: TestCmdSiteDelete_ValidateInput (0.13s)
    --- PASS: TestCmdSiteDelete_ValidateInput/site_name_is_not_specified (0.00s)
    --- PASS: TestCmdSiteDelete_ValidateInput/site_name_is_not_specified,_all (0.00s)
    --- PASS: TestCmdSiteDelete_ValidateInput/site_name_is_nil (0.00s)
    --- PASS: TestCmdSiteDelete_ValidateInput/site_name_is_not_valid (0.00s)
    --- PASS: TestCmdSiteDelete_ValidateInput/more_than_one_argument_is_specified (0.00s)
    --- PASS: TestCmdSiteDelete_ValidateInput/site_doesn't_exist (0.00s)
    --- FAIL: TestCmdSiteDelete_ValidateInput/kubernetes_flags_are_not_valid_on_this_platform (0.00s)

At first glance I'm not sure what could be wrong. I suspect using ~/.local/share could be a part of the problem if other tests are also manipulating that filesystem.

[fgiorgetti]

I never saw it before, but I have noticed some tests are actually using ~/.local/share to store data,
that could certainly lead to conflicts.