[adapter] Use context without cancel for GC

The GC triggered in a goroutine after the Convert operation is done was called with the same context passed down. However, when the convert action is called synchronously (accelctl --sync), the associated context is canceled when the sync operation is completed. Since the GC was run after, it was failing with a `context canceled` error.
To solve this, we now remove the `cancel` from the context passed down to the GC.

Signed-off-by: Baptiste Girard-Carrabin <baptiste.girardcarrabin@datadoghq.com>

Author: Fricounet

pkg/adapter/adapter.go

@@ -137,7 +137,7 @@ func (adp *LocalAdapter) Convert(ctx context.Context, source string) (*converter
 		}
 		return nil, err
 	}
-	go adp.content.GC(ctx, adp.content.Threshold)
+	go adp.content.GC(context.WithoutCancel(ctx), adp.content.Threshold)
 	return metric, nil
 }