[Integration Test Framework] Dump process list on first failure

[ycombinator]

Currently, when an integration test fails, we dump the process list to help debug the failure, by registering a t.Cleanup() callback:

elastic-agent/pkg/testing/fixture_install.go

Lines 219 to 226 in e8962b0

	f.t.Cleanup(func() {
	if f.t.Failed() {
	procs := getProcesses(f.t, `.*`)
	dir, err := findProjectRoot(f.caller)
	if err != nil {
	f.t.Logf("failed to dump process; failed to find project root: %s", err)
	return
	}

However, this callback registration is happening after the test attempts to install Elastic Agent:

elastic-agent/pkg/testing/fixture_install.go

Lines 180 to 194 in e8962b0

	if installOpts == nil {
	// default options when not provided
	installOpts = &InstallOpts{}
	}
	installArgs := []string{"install"}
	installOptsArgs, err := installOpts.toCmdArgs(f.operatingSystem)
	if err != nil {
	return nil, err
	}
	installArgs = append(installArgs, installOptsArgs...)
	out, err := f.Exec(ctx, installArgs, opts...)
	if err != nil {
	return out, fmt.Errorf("error running agent install command: %w", err)
	}

Consequently, if the install itself fails, we do not get a dump of the process list.

We should make it so the process list is dumped on the earliest failure of any integration test.

[elasticmachine]

Pinging @elastic/elastic-agent-control-plane (Team:Elastic-Agent-Control-Plane)