[extension/zpages] remove mention of rpcz (#9329)

**Description:**
Remove mention of rpcz from tests and README.

**Link to tracking Issue:**
Fixes #9328

.chloggen/remove_rpcz.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: zpagesextension
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Remove mention of rpcz page from zpages extension
+
+# One or more tracking issues or pull requests related to the change
+issues: [9328]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

extension/zpagesextension/README.md

@@ -75,9 +75,3 @@ example
 They also allow you to quickly examine error samples
 
 Example URL: http:https://localhost:55679/debug/tracez
-
-### RpcZ
-The Rpcz route is available to help examine statistics of remote procedure calls (RPCs) 
-that are properly instrumented. For example when using gRPC
-
-Example URL: http:https://localhost:55679/debug/rpcz

service/service_test.go

@@ -493,8 +493,6 @@ func assertMetrics(t *testing.T, metricsAddr string, expectedLabels map[string]l
 func assertZPages(t *testing.T, zpagesAddr string) {
  paths := []string{
  "/debug/tracez",
- // TODO: enable this when otel-metrics is used and this page is available.
- // "/debug/rpcz",
  "/debug/pipelinez",
  "/debug/servicez",
  "/debug/extensionz",