chore: change the setupchannel caller level from warn (#754)

# Description

Linuxutil and packetforward plugin, these SetupChannel func are not
supported setup channel; in order to reduce the unnecessary error log in
Kusto, we change the caller level

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pkg/plugin/linuxutil/linuxutil_linux.go

@@ -51,7 +51,7 @@ func (lu *linuxUtil) Start(ctx context.Context) error {
 }
 
 func (lu *linuxUtil) SetupChannel(ch chan *hubblev1.Event) error {
-	lu.l.Warn("Plugin does not support SetupChannel", zap.String("plugin", string(Name)))
+	lu.l.Debug("Plugin does not support SetupChannel", zap.String("plugin", string(Name)))
 	return nil
 }
 

pkg/plugin/packetforward/packetforward_linux.go

@@ -193,7 +193,7 @@ func (p *packetForward) Stop() error {
 }
 
 func (p *packetForward) SetupChannel(ch chan *hubblev1.Event) error {
-	p.l.Warn("SetupChannel is not supported by plugin", zap.String("plugin", string(Name)))
+	p.l.Debug("SetupChannel is not supported by plugin", zap.String("plugin", string(Name)))
 	return nil
 }