Flaky test in instrgen/driver

[dmathieu]

Description

the instrgen package has a flaky test.
https://github.com/open-telemetry/opentelemetry-go-contrib/actions/runs/12176159393/job/33961307884

--- FAIL: TestInstrumentation (6.97s)
    instrgen_test.go:87: 
        	Error Trace:	/Users/runner/work/opentelemetry-go-contrib/opentelemetry-go-contrib/instrgen/driver/instrgen_test.go:87
        	Error:      	Should be true
        	Test:       	TestInstrumentation
        	Messages:   	testdata/interface/app/impl.go_pass_tracing
    instrgen_test.go:87: 
        	Error Trace:	/Users/runner/work/opentelemetry-go-contrib/opentelemetry-go-contrib/instrgen/driver/instrgen_test.go:87
        	Error:      	Should be true
        	Test:       	TestInstrumentation
        	Messages:   	testdata/interface/main.go_pass_tracing

The full output also gives stack traces. Those do not look like panics though. So they may be debug lines?

cc @MrAlias as @pdelewski as code owners.