test: Add test for historic PCP data
test: Add test for historic PCP data

Commit d6fdd2a283b9f fixed the loading of compressed PCP archives (for
data older than a day). Add a corresponding integration test case to
make sure this stays working.

This also lays a test basis for the upcoming performance problem
debugging work.

See https://bugzilla.redhat.com/show_bug.cgi?id=1804844

Closes #14352

mvollmer/cockpit,cockpit-project/cockpit,deryni/cockpit,garrett/cockpit,deryni/cockpit,garrett/cockpit,moraleslazaro/cockpit,deryni/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,deryni/cockpit,martinpitt/cockpit,cockpit-project/cockpit,deryni/cockpit,mvollmer/cockpit,martinpitt/cockpit,deryni/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,garrett/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,garrett/cockpit,cockpit-project/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,deryni/cockpit,garrett/cockpit,cockpit-project/cockpit,martinpitt/cockpit,moraleslazaro/cockpit