Add inject flag for disabling tap

[adleong]

Add a --disable-tap flag to inject which prevents the pod from being tapped by instructing the proxy to not expose a tap server.

• Introduce a proxy environment variable to disable the tap server
• Add an inject flag to set the proxy env var
• Also set an annotation on the pod to indicate that tap has been disabled on that pod so that the control plane knows to exclude that pod from any taps