Update Nginx Ingress to use ImplementationSpecific pathType to avoid admission controller issues (#2215)

Summary: Update Nginx Ingress to use `ImplementationSpecific` pathType
to avoid admission controller issues

Nginx Ingress
[v1.8.0](https://github.com/kubernetes/ingress-nginx/blob/311a2082c5622c7bdaff24273110e6f2a0f3b5da/changelog/controller-1.8.0.md?plain=1#L16)
introduced a `strict-validate-path-type` setting that defaults to true.
This causes the existing pathType used by Pixie's manifest to be blocked
by the Nginx Ingress admission controller. Updating this value to
`ImplementationSpecific` side steps this validation, so it can be
created successfully.

> For improving security, our 1.8.0 release includes a [new, optional
validation
](https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/configmap/#strict-validate-path-type)that
limits the characters accepted on ".spec paths.path" when pathType=Exact
or pathType=Prefix, to alphanumeric characters only.

Relevant Issues: #2214

Type of change: /kind bugfix

Test Plan: Deployed to a cluster using Nginx Ingress

Changelog Message: Fixed an issue where Nginx Ingress resource creation
would be blocked by admission controller (on Nginx Ingress v1.8.0 and
later)

Signed-off-by: Dom Del Nano <ddelnano@gmail.com>

Author: ddelnano

k8s/cloud/overlays/exposed_services_nginx/cloud_ingress_grpcs.yaml

@@ -20,21 +20,21 @@ spec:
     http:
       paths:
       - path: /px.services.(.*)
-        pathType: Prefix
+        pathType: ImplementationSpecific
         backend:
           service:
             name: vzconn-service
             port:
               number: 51600
       - path: /px.cloudapi.(.*)
-        pathType: Prefix
+        pathType: ImplementationSpecific
         backend:
           service:
             name: api-service
             port:
               number: 51200
       - path: /px.api.(.*)
-        pathType: Prefix
+        pathType: ImplementationSpecific
         backend:
           service:
             name: cloud-proxy-service
@@ -44,21 +44,21 @@ spec:
     http:
       paths:
       - path: /px.services.(.*)
-        pathType: Prefix
+        pathType: ImplementationSpecific
         backend:
           service:
             name: vzconn-service
             port:
               number: 51600
       - path: /px.cloudapi.(.*)
-        pathType: Prefix
+        pathType: ImplementationSpecific
         backend:
           service:
             name: api-service
             port:
               number: 51200
       - path: /px.api.(.*)
-        pathType: Prefix
+        pathType: ImplementationSpecific
         backend:
           service:
             name: cloud-proxy-service