usagestats tests: don't check unpredictable number (#5840)

If this test is run alongside a number of other tests then the number of
goroutines can change between when the report is generated and when the
result is checked, which will cause the test to fail.

pkg/usagestats/stats_test.go

@@ -50,7 +50,7 @@ func Test_BuildReport(t *testing.T) {
 	require.Equal(t, r.Edition, "OSS")
 	require.Equal(t, r.Target, "compactor")
 	require.Equal(t, r.Metrics["num_cpu"], runtime.NumCPU())
-	require.Equal(t, r.Metrics["num_goroutine"], runtime.NumGoroutine())
+	// Don't check num_goroutine because it could have changed since the report was created.
 	require.Equal(t, r.Metrics["compression"], "lz4")
 	require.Equal(t, r.Metrics["compression_ratio"], int64(100))
 	require.Equal(t, r.Metrics["size_mb"], 200.1)