Pull request: all: rm var shadowing, vol. 2

Updates #2803.

Squashed commit of the following:

commit bf7186378164f19ea9e21ec832526792efa2f9c3
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Mar 11 19:48:17 2021 +0300

    all: rm var shadowing, vol. 2

internal/querylog/search.go

@@ -118,8 +118,9 @@ func (l *queryLog) searchFiles(params *searchParams) ([]*logEntry, time.Time, in
 	// The idea is to make search calls faster so that the UI could handle it and show something
 	// This behavior can be overridden if "maxFileScanEntries" is set to 0
 	for total < params.maxFileScanEntries || params.maxFileScanEntries <= 0 {
-		entry, ts, err := l.readNextEntry(r, params)
-
+		var entry *logEntry
+		var ts int64
+		entry, ts, err = l.readNextEntry(r, params)
 		if err == io.EOF {
 			// there's nothing to read anymore
 			break