fix: close default apm tracer (elastic#17293)

the default tracer is leaking and its background goroutine
spamming requests to this apm server (default endpoint)
If TLS is enabled it causes 'http request sent to https endpoint'.

Close the default tracer since it's not used.

Author: kruskall

internal/beater/beater.go

@@ -124,6 +124,12 @@ type RunnerParams struct {
 func NewRunner(args RunnerParams) (*Runner, error) {
 	fips140.CheckFips()
 
+	// the default tracer is leaking and its background
+	// goroutine is spamming requests to this apm server (default endpoint)
+	// If TLS is enabled it causes "http request sent to https endpoint".
+	// Close the default tracer since it's not used.
+	apm.DefaultTracer().Close()
+
 	var unpackedConfig struct {
 		APMServer  *agentconfig.C        `config:"apm-server"`
 		Output     agentconfig.Namespace `config:"output"`