Add test connecting to update sites

[daniel-beck]

Trying to reproduce https://groups.google.com/g/jenkinsci-dev/c/WeLLd7cJrCo

CC @kuisathaverat

[daniel-beck]

Locally 79302b0 changes the test durations from

[INFO] Running io.jenkins.plugins.jenkins_infra_test.InjectedTest
[INFO] Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 3.548 s -- in io.jenkins.plugins.jenkins_infra_test.InjectedTest
[INFO] Running io.jenkins.plugins.jenkinsinfratest.UpdateCenterTest
[INFO] Tests run: 16, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 16.12 s -- in io.jenkins.plugins.jenkinsinfratest.UpdateCenterTest

to

[INFO] Running io.jenkins.plugins.jenkins_infra_test.InjectedTest
[INFO] Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 9.992 s -- in io.jenkins.plugins.jenkins_infra_test.InjectedTest
[INFO] Running io.jenkins.plugins.jenkinsinfratest.UpdateCenterTest
[INFO] Tests run: 16, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 104.9 s -- in io.jenkins.plugins.jenkinsinfratest.UpdateCenterTest

indicating the plugin is extremely heavy. So perhaps the test failures in infra are just due to reaching some agent capacity threshold there?

[kuisathaverat]

We tracked the issue to a change in the Jenkins file to use more threads, so we are hitting a resource limit.

jenkinsci/opentelemetry-plugin@cd1906b