Use logp.NewNopLogger for TestGenerateProcessorList (#47316) (#47319)

Because logptest.NewTestingLogger uses the testing.T as the output for
the logger, it could happen that the processors would log after the
test had ended, leading to a panic.

This commit fixes it by using a no-op logger instead.

(cherry picked from commit 34f3c91)

Co-authored-by: Tiago Queiroz <tiago.queiroz@elastic.co>

Author: mergify[bot]

libbeat/publisher/processing/default_test.go

@@ -32,7 +32,6 @@ import (
 	"github.com/elastic/beats/v7/libbeat/processors/actions/addfields"
 	"github.com/elastic/elastic-agent-libs/config"
 	"github.com/elastic/elastic-agent-libs/logp"
-	"github.com/elastic/elastic-agent-libs/logp/logptest"
 	"github.com/elastic/elastic-agent-libs/mapstr"
 
 	_ "github.com/elastic/beats/v7/libbeat/processors/add_cloud_metadata"
@@ -52,7 +51,7 @@ func TestGenerateProcessorList(t *testing.T) {
 	plugins, err := processors.NewPluginConfigFromList(inputCfg)
 	require.NoError(t, err)
 
-	processors, err := processors.New(plugins, logptest.NewTestingLogger(t, ""))
+	processors, err := processors.New(plugins, logp.NewNopLogger())
 	require.NoError(t, err)
 	// make sure the processor init got the config formatted in a way it expected
 	require.Equal(t, 4, len(processors.List))