[testbed] Remove deprecated GetAvailablePort function

.chloggen/remove_deprecate_GetAvailablePort.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: testbed
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Remove deprecated `GetAvailablePort` function
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [32800]
+
+# (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:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# 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: []

testbed/testbed/in_process_collector_test.go

@@ -9,12 +9,14 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/internal/common/testutil"
 )
 
 func TestNewInProcessPipeline(t *testing.T) {
 	factories, err := Components()
 	assert.NoError(t, err)
-	sender := NewOTLPTraceDataSender(DefaultHost, GetAvailablePort(t))
+	sender := NewOTLPTraceDataSender(DefaultHost, testutil.GetAvailablePort(t))
 	receiver := NewOTLPDataReceiver(DefaultOTLPPort)
 	runner, ok := NewInProcessCollector(factories).(*inProcessCollector)
 	require.True(t, ok)

testbed/testbed/mock_backend_test.go

@@ -9,10 +9,12 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/internal/common/testutil"
 )
 
 func TestGeneratorAndBackend(t *testing.T) {
-	port := GetAvailablePort(t)
+	port := testutil.GetAvailablePort(t)
 
 	tests := []struct {
 		name     string