Update net-istio nightly (#11576)
Update net-istio nightly (#11576)

bumping knative.dev/net-istio ef6c1a6...fded5b7:
  > fded5b7 upgrade to latest dependencies (# 687)
  > 64d6fe4 fix webhook name (# 686)
  > 70b3fb9 include v1 for admission review version (# 685)
  > 44289f0 Use terminationDrainDuration in MeshConfig.defaultConfig (# 682)
  > c634a2c rename to be consistent with various net-* repos (# 683)

Signed-off-by: Knative Automation <f415700d4d0ce1c81810fe7553e3eea2bed16231@knative.team>
knative/serving,knative/serving