[Synthetics] Add a guided card for synthetics (#159863)

Adds a guided card for synthetics. Guided onboarding is only available
in cloud, so in order to test it locally you can add `xpack.cloud.id:
test` setting to your `kibana.dev.yml` file. You can find more
information in the [guided onboarding
docs](https://github.com/elastic/kibana/tree/main/src/plugins/guided_onboarding#development).


f146bc08-a1a4-4d4f-891b-574b71584eba

Part of https://github.com/elastic/kibana/issues/159562

---------

Co-authored-by: Casper Hübertz <casper@formgeist.com>
Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>

packages/kbn-guided-onboarding/src/components/landing_page/__snapshots__/guide_cards.test.tsx.snap

@@ -219,6 +219,33 @@ exports[`guide cards snapshots should render all cards 1`] = `
           size="m"
         />
       </EuiFlexItem>
+      <EuiFlexItem
+        grow={false}
+        key="4"
+      >
+        <GuideCard
+          activateGuide={[MockFunction]}
+          activeFilter="all"
+          card={
+            Object {
+              "icon": "videoPlayer",
+              "navigateTo": Object {
+                "appId": "synthetics",
+                "path": "/monitors/getting-started",
+              },
+              "order": 14,
+              "solution": "observability",
+              "telemetryId": "onboarding--observability--synthetics",
+              "title": "Create a Synthetic Monitor",
+            }
+          }
+          guidesState={Array []}
+          navigateToApp={[MockFunction]}
+        />
+        <EuiSpacer
+          size="m"
+        />
+      </EuiFlexItem>
     </EuiFlexGroup>
   </EuiFlexItem>
   <EuiFlexItem

packages/kbn-guided-onboarding/src/components/landing_page/guide_cards.constants.tsx

@@ -131,6 +131,22 @@ export const guideCards: GuideCardConstants[] = [
     telemetryId: 'onboarding--observability--kubernetes',
     order: 11,
   },
+  {
+    solution: 'observability',
+    icon: 'videoPlayer',
+    title: i18n.translate(
+      'guidedOnboardingPackage.gettingStarted.cards.syntheticsObservability.title',
+      {
+        defaultMessage: 'Create a Synthetic Monitor',
+      }
+    ),
+    navigateTo: {
+      appId: 'synthetics',
+      path: '/monitors/getting-started',
+    },
+    telemetryId: 'onboarding--observability--synthetics',
+    order: 14,
+  },
   {
     solution: 'security',
     icon: 'securitySignal',