Pull request 2039: 6304-fix-ring-buffer

Updates #6304.

Squashed commit of the following:

commit 7382630404cf18ff45e54234134c192161f5d94a
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Thu Oct 12 19:37:01 2023 +0300

    all: upd chlog

commit ff9a82a6872f3bd93fe89956c5441429c189bce7
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Thu Oct 12 19:27:35 2023 +0300

    querylog: fix ring buffer

internal/querylog/qlog.go

@@ -139,7 +139,7 @@ func (l *queryLog) clear() {
 		l.bufferLock.Lock()
 		defer l.bufferLock.Unlock()
 
-		l.buffer = nil
+		l.buffer.Clear()
 		l.flushPending = false
 	}()