OTel: Access the Custom Services Entry Point

- Add empty ModeCustomServices page as the navigable target
- Register the mode (mode_registry) for Ultimate, UltimateMT and Cloud
- Wire the entry point into UltimateMT (was missing)
- Add E2E test + page object for navigating to the page
- Update wato menu snapshot tests for all three editions

CMK-36034

Change-Id: I4818bf6d753fb94d878ad6e1a64ed9fd88581914

Author: m3hransh

module_layers.toml

@@ -1006,7 +1006,7 @@ allows = [
   "cmk.multi_tenancy.shared",
   "cmk.metric_backend.gui",
   "cmk.otel_collector.gui",
-  "cmk.telemetry.gui.register",
+  "cmk.telemetry.gui",
   "cmk.piggyback",
   "cmk.robotmk.gui",
   "cmk.ruleset_matcher",
@@ -1034,7 +1034,7 @@ allows = [
   "cmk.liveproxyd.gui",
   "cmk.metric_backend.gui.register",
   "cmk.otel_collector.gui",
-  "cmk.telemetry.gui.register",
+  "cmk.telemetry.gui",
   "cmk.shared_typing",
   "cmk.utils.agent_registration",
   "cmk.utils.config_warnings",
@@ -1780,6 +1780,7 @@ allows = [
   "cmk.fields",
   "cmk.gui",
   "cmk.metric_backend.gui",
+  "cmk.otel_collector.gui",
   "cmk.shared_typing.vue_formspec_components",
   "cmk.telemetry.host_name_template",
 ]

tests/system/gui/testlib/playwright/pom/setup/otel/custom_services.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+# Copyright (C) 2026 Checkmk GmbH - License: GNU General Public License v2
+# This file is part of Checkmk (https://checkmk.com). It is subject to the terms and
+# conditions defined in the file COPYING, which is part of this source code package.
+import logging
+import re
+from typing import override
+
+from playwright.sync_api import Locator
+
+from tests.system.gui.testlib.playwright.helpers import DropdownListNameToID
+from tests.system.gui.testlib.playwright.pom.page import CmkPage
+
+logger = logging.getLogger(__name__)
+
+
+class CustomServices(CmkPage):
+    """Represent the page `Setup -> Telemetry -> Custom Services`."""
+
+    page_title = "Custom Services"
+    main_menu_name = "Custom Services"
+    empty_state_text = "No custom services yet"
+
+    @override
+    def navigate(self) -> None:
+        logger.info("Navigate to '%s' page", self.page_title)
+        self.click_and_wait_for_navigation(
+            self.main_menu.setup_menu(self.main_menu_name, exact=True),
+            frame_url=re.compile("mode=otel_custom_services"),
+        )
+        self.validate_page()
+
+    @override
+    def validate_page(self) -> None:
+        logger.info("Validate that current page is '%s' page", self.page_title)
+        self.main_area.check_page_title(self.page_title)
+
+    @override
+    def _dropdown_list_name_to_id(self) -> DropdownListNameToID:
+        return DropdownListNameToID()
+
+    @property
+    def empty_state(self) -> Locator:
+        return self.main_area.locator("div.no-config-bundles")