Dashboards: Remove dummy trim dashboard api (#77249)

Co-authored-by: nikimanoledaki <niki.manoledaki@grafana.com>

pkg/services/featuremgmt/usage_stats_test.go

@@ -9,7 +9,6 @@ import (
 
 func TestFeatureUsageStats(t *testing.T) {
 	featureManagerWithAllFeatures := WithFeatures(
-		"trimDefaults",
 		"database_metrics",
 		"live-config",
 		"UPPER_SNAKE_CASE",
@@ -17,7 +16,6 @@ func TestFeatureUsageStats(t *testing.T) {
 	)
 
 	require.Equal(t, map[string]any{
-		"stats.features.trim_defaults.count":      1,
 		"stats.features.database_metrics.count":   1,
 		"stats.features.live_config.count":        1,
 		"stats.features.upper_snake_case.count":   1,