Enable execution context tracking for SLO, infra and synthetics plugins (#204939)

## Summary

This PR enables default execution context tracking (which was added in
this [PR](https://github.com/elastic/kibana/pull/204547)) for the
following plugins:

- SLO
- Infra
- Synthetics

|Plugin|Before|After|
|---|---|---|

|SLO|![image](ae76d68d-2970-4aaf-816a-05c161b1e4fe)|

|Synthetics|![image](a016cc78-121a-4381-8786-9ef96f20c028)|
|Infra >
Inventory|![image](d4da56b8-581c-4be1-bd33-8a62b602392e)|
|Infra >
Hosts|![image](4138f985-bf3e-477a-ba71-d6f0e3483ef8)|

x-pack/solutions/observability/plugins/infra/public/pages/metrics/index.tsx

@@ -118,7 +118,7 @@ export const InfrastructurePage = () => {
                 </HeaderMenuPortal>
               )}
 
-              <Routes>
+              <Routes enableExecutionContextTracking={true}>
                 <Route path="/inventory" component={SnapshotPage} />
                 {config.featureFlags.metricsExplorerEnabled && (
                   <Route path="/explorer" component={MetricsExplorerPage} />

x-pack/solutions/observability/plugins/slo/public/application.tsx

@@ -145,7 +145,7 @@ function App() {
   const routes = getRoutes(isServerless);
 
   return (
-    <Routes>
+    <Routes enableExecutionContextTracking={true}>
       {Object.keys(routes).map((path) => {
         const { handler, exact } = routes[path];
         const Wrapper = () => {

x-pack/solutions/observability/plugins/synthetics/public/apps/synthetics/routes.tsx

@@ -189,7 +189,7 @@ export const PageRouter: FC = () => {
   const isUnprivileged = useSyntheticsPrivileges();
 
   return (
-    <Routes>
+    <Routes enableExecutionContextTracking={true}>
       {routes.map(
         ({
           title,