fixed Multiple instances cache goroutine leaks #2373

[hktalent]

Proposed changes

Checklist

• Pull request is created against the dev branch
• All checks passed (lint, unit/integration/regression tests etc.) with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[hktalent]

@ehsandeep
Local concurrent, multi-instance nuclei tests for several days to confirm that there is no cache leak

[hktalent]

How to test for cache memory leaks?
Start debug mode

import (
"net/http"
_ "net/http/pprof"
)
go func() {
http.ListenAndServe(":6060", nil)
}()

After calling nuclei to scan,
run
go tool pprof -seconds=10 -http=:9999 http://localhost:6060/debug/pprof/heap
Open browser access;
http://127.0.0.1:6060/debug/pprof/goroutine?debug=2
You can see that the cache always exists

[ehsandeep]

Closing as duplicate of #2390