systemd/services: Fix event handler race leading to wrong page switch

Event handlers are all async. It sometimes happened that clicking on a
unit in the list, or the test changing the URL to a particular unit, for
attempting to open the details page. This triggered the
`onOptionsChanged` handler, which  would reset the path back to the
list. With some added debug logging, the logs look like this:

> ServicesPageBody render list for path []
> Clicked on service in list, going to condtest.service
> cockpit.location.get; window.location.hash "#/?type=service"
> cockpit.Location.go: changed window.location.hash to #/condtest.service?type=service
-> wait: ph_collected_text_is("#statuses .status","Not runningAutomatically starts")
> cockpit.location.get; window.location.hash "#/condtest.service?type=service" creating new last_loc
> ServicesPageBody onOptionsChanged; cockpit.location {"url_root":"","path":["condtest.service"],"options":{"type":"service"},"href":"/condtest.service?type=service"} merged options {"type":"service"} calling go to services list; path prop []

^ i.e. here the onOptionsChanged fired, and reset the path back to `[]`.
We can't use `this.props.path` either, as that hasn't been updated yet.

> cockpit.location.get; window.location.hash "#/condtest.service?type=service" unchanged last_loc
> cockpit.Location.go: changed window.location.hash to #/?type=service
> locationchanged {"type":"service"}
> usePageLocation changed {"url_root":"","path":[],"options":{"type":"service"},"href":"/?type=service"}

So the details page often was not actually opened. Fix that by not
hardcoding the target path to `[]`, but using the current one instead.
This allows event handlers to be delayed even until after a page change.

Fixes cockpit-project#18443

pkg/systemd/services/services.jsx

@@ -227,7 +227,7 @@ class ServicesPageBody extends React.Component {
         if (!currentOptions.name)
             delete currentOptions.name;
 
-        cockpit.location.go([], currentOptions);
+        cockpit.location.go(cockpit.location.path, currentOptions);
     }
 
     componentDidMount() {
@@ -1024,7 +1024,7 @@ const ServicesPage = () => {
 
     const activeTab = options.type || 'service';
     const owner = options.owner || 'system';
-    const setOwner = (owner) => cockpit.location.go([], Object.assign(options, { owner }));
+    const setOwner = (owner) => cockpit.location.go(cockpit.location.path, Object.assign(options, { owner }));
 
     if (owner !== 'system' && owner !== 'user') {
         console.warn("not a valid location: " + path);
@@ -1041,7 +1041,7 @@ const ServicesPage = () => {
                         <ServiceTabs activeTab={activeTab}
                                       tabErrors={tabErrors}
                                       onChange={activeTab => {
-                                          cockpit.location.go([], Object.assign(options, { type: activeTab }));
+                                          cockpit.location.go(cockpit.location.path, Object.assign(options, { type: activeTab }));
                                       }} />
                         <FlexItem align={{ default: 'alignRight' }}>
                             {loggedUser && loggedUser !== 'root' && <ToggleGroup>