The InstalledFile of dpkg package should exclude directories

[knqyf263]

Description

The logic to exclude directories doesn't work in cases where a list of files/dirs is not sorted.

trivy/pkg/fanal/analyzer/pkg/dpkg/dpkg.go

Lines 126 to 135 in 164b025

	// Add the file if it is not directory.
	// e.g.
	// /usr/sbin
	// /usr/sbin/tarcat
	//
	// In the above case, we should take only /usr/sbin/tarcat since /usr/sbin is a directory
	if !strings.HasPrefix(current, previous+"/") {
	installedFiles = append(installedFiles, previous)
	}
	previous = current

Discussed in #6543

[y4ney]

Hi,@knqyf263 ! I have submitted a PR #6551 to address this issue and would appreciate your review.