Attempt at fixing the memory usage in CI (#19171)

- Do not keep many intervals of the in memory sink metrics
   collector. Otherwise we fill up the CI's memory

builtin/logical/pki/path_tidy_test.go

@@ -421,8 +421,8 @@ func TestCertStorageMetrics(t *testing.T) {
 
 	// We set up a metrics accumulator
 	inmemSink := metrics.NewInmemSink(
-		2*newPeriod, // A short time period is ideal here to test metrics are emitted every periodic func
-		2000000*time.Hour)
+		2*newPeriod,  // A short time period is ideal here to test metrics are emitted every periodic func
+		10*newPeriod) // Do not keep a huge amount of metrics in the sink forever, clear them out to save memory usage.
 
 	metricsConf := metrics.DefaultConfig("")
 	metricsConf.EnableHostname = false