Revert "Require npm >=6.9.0 (#10817)" (#10877)
Revert "Require npm >=6.9.0 (#10817)" (#10877)

This reverts commit dad1c19773a326c3111d72d88f0215b27ee0d9ea.
dylan-smith/vso-agent-tasks,dylan-smith/vso-agent-tasks,Microsoft/vsts-tasks,dylan-smith/vso-agent-tasks,Microsoft/vsts-tasks,Microsoft/vsts-tasks,Microsoft/vso-agent-tasks,Microsoft/vso-agent-tasks,dylan-smith/vso-agent-tasks,dylan-smith/vso-agent-tasks,Microsoft/vsts-tasks,Microsoft/vsts-tasks,Microsoft/vso-agent-tasks