Remove un-necessary INGRESSGATEWAY variables.

Using a variable makes the commands longer and doesn't provide any benefit since:
1. the variable name is almost as long as the value.
2. it's only used a single time

Author: alanconway

02-basics/bin/call.sh

@@ -1,6 +1,5 @@
 #!/bin/bash
 
-INGRESSGATEWAY=istio-ingressgateway
-IP_ADDRESS="$(minishift ip):$(kubectl get svc $INGRESSGATEWAY --namespace istio-system --output 'jsonpath={.spec.ports[?(@.port==80)].nodePort}')"
+IP_ADDRESS="$(minishift ip):$(kubectl get svc istio-ingressgateway --namespace istio-system --output 'jsonpath={.spec.ports[?(@.port==80)].nodePort}')"
 
 curl -H "Host:greeter.knativetutorial.example.com" $IP_ADDRESS

03-configs-and-routes/bin/call.sh

@@ -2,8 +2,7 @@
 
 set -e 
 
-INGRESSGATEWAY=istio-ingressgateway
-IP_ADDRESS="$(minishift ip):$(kubectl get svc $INGRESSGATEWAY --namespace istio-system --output 'jsonpath={.spec.ports[?(@.port==80)].nodePort}')"
+IP_ADDRESS="$(minishift ip):$(kubectl get svc istio-ingressgateway --namespace istio-system --output 'jsonpath={.spec.ports[?(@.port==80)].nodePort}')"
 
 while true
 do

documentation/modules/ROOT/pages/_partials/invoke-service.adoc

@@ -6,8 +6,7 @@
 [#{k8s-env}-svc-gateway-env]
 [source,bash,subs="+macros,+attributes"]
 ----
-INGRESSGATEWAY=istio-ingressgateway
-IP_ADDRESS="$({k8s-env} ip):$({k8s-cli} get svc $INGRESSGATEWAY --namespace istio-system --output 'jsonpath={.spec.ports[?(@.port==80)].nodePort}')"
+IP_ADDRESS="$({k8s-env} ip):$({k8s-cli} get svc istio-ingressgateway --namespace istio-system --output 'jsonpath={.spec.ports[?(@.port==80)].nodePort}')"
 ----
 copyToClipboard::{k8s-env}-svc-gateway-env[]