Plugins: Handle app plugin proxy routes per request (#51835)

Fixes #47530

pkg/api/plugin_proxy_test.go

@@ -0,0 +1,36 @@
+package api
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestExtractPluginProxyPath(t *testing.T) {
+	testCases := []struct {
+		originalRawPath string
+		exp             string
+	}{
+		{
+			"/api/plugin-proxy/test",
+			"",
+		},
+		{
+			"/api/plugin-proxy/test/some/thing",
+			"some/thing",
+		},
+		{
+			"/api/plugin-proxy/test2/api/services/afsd%2Fafsd/operations",
+			"api/services/afsd%2Fafsd/operations",
+		},
+		{
+			"/api/plugin-proxy/cloudflare-app/with-token/api/v4/accounts",
+			"with-token/api/v4/accounts",
+		},
+	}
+	for _, tc := range testCases {
+		t.Run("Given raw path, should extract expected proxy path", func(t *testing.T) {
+			assert.Equal(t, tc.exp, extractProxyPath(tc.originalRawPath))
+		})
+	}
+}