bug(k8s): k8s scan works too long

[afdesk]

Description

Trivy kubernetes scan takes a lot of time for small minikube cluster:

$ time trivy k8s --report summary --debug --disable-node-collector --timeout 30m0s  
491,23s user 49,05s system 55% cpu 16:21,43 total

As said in #7661 Trivy fails even for test environment.

Reason

Trivy creates a new scanner for each kubernetes artifact:

trivy/pkg/k8s/scanner/scanner.go

Line 158 in ab3a3b2

imageReport, err := s.runner.ScanImage(ctx, opts)

trivy/pkg/k8s/scanner/scanner.go

Line 184 in ab3a3b2

configReport, err := s.runner.ScanFilesystem(ctx, s.opts)

Solution

As an idea we can try to optimize using of scanners.

Reproduction Steps

$ trivy k8s --report summary --debug --disable-node-collector --timeout 30m0s  

Discussed in #7661