fix: change so that second SIGINT signal immediately exits program (#…

…2598)

## Description

This changes the behavior so that the second SIGINT signal immediately
exits. This is useful if a process is not quitting in context cancel or
if it is taking too long to quit.

## Related Issue

Relates to #2594 

## Checklist before merging

- [x] Test, docs, adr added or updated as needed
- [x] [Contributor Guide
Steps](https://github.com/defenseunicorns/zarf/blob/main/.github/CONTRIBUTING.md#developer-workflow)
followed

main.go

@@ -7,6 +7,7 @@ package main
 import (
 	"context"
 	"embed"
+	"os"
 	"os/signal"
 	"syscall"
 
@@ -22,8 +23,22 @@ var cosignPublicKey string
 var zarfSchema embed.FS
 
 func main() {
-	ctx, cancel := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
+	signalCh := make(chan os.Signal, 1)
+	signal.Notify(signalCh, syscall.SIGINT, syscall.SIGTERM)
+	go func() {
+		first := true
+		for {
+			<-signalCh
+			if first {
+				first = false
+				cancel()
+				continue
+			}
+			os.Exit(1)
+		}
+	}()
 
 	config.CosignPublicKey = cosignPublicKey
 	lint.ZarfSchema = zarfSchema