devcontainer.json: remove `--privileged`

We needed it to ensure that gem5's `PerfKvmCounter::attach()` would work but with simbricks/simbricks#109 this has become unnecessary.

.devcontainer.json

 {
 	"image": "simbricks/simbricks-build:latest",
 	"runArgs": [
-		"--device=/dev/kvm",
-		"--privileged"
+		"--device=/dev/kvm"
 	],
 	"extensions": [
 		"ms-python.python"