[Logs onboarding] Making onboarding boxes clickable (#166422)

Closes https://github.com/elastic/kibana/issues/166000.

### Before

![image](cbb66ff5-3a84-4ad6-88de-14e8f98c0c6a)

### After
<img width="936" alt="image"
src="ba886167-c073-45da-99b0-36607a81b50c">

### How to test
1. Go to[ logs
onboarding](https://yngrdyn-deploy-kiban-pr166422.kb.us-west2.gcp.elastic-cloud.com/app/observabilityOnboarding)
landing page
2. Verify the folllowing
- Cards are clickable. `Get started` buttons should remain clickable as
well.
    - Cards description is centered

x-pack/plugins/observability_onboarding/public/components/app/home/index.tsx

@@ -139,11 +139,12 @@ export function Home() {
               paddingSize="l"
               display="plain"
               hasBorder
+              onClick={handleClickSystemLogs}
             >
               <EuiSpacer size="s" />
               <EuiBadge color="hollow">{elasticAgentLabel}</EuiBadge>
               <EuiSpacer size="m" />
-              <EuiText color="subdued" size="s" textAlign="left">
+              <EuiText color="subdued" size="s" textAlign="center">
                 <p>
                   {i18n.translate(
                     'xpack.observability_onboarding.card.systemLogs.description1',
@@ -177,11 +178,12 @@ export function Home() {
               paddingSize="l"
               display="plain"
               hasBorder
+              onClick={handleClickCustomLogs}
             >
               <EuiSpacer size="s" />
               <EuiBadge color="hollow">{elasticAgentLabel}</EuiBadge>
               <EuiSpacer size="m" />
-              <EuiText color="subdued" size="s" textAlign="left">
+              <EuiText color="subdued" size="s" textAlign="center">
                 <p>
                   {i18n.translate(
                     'xpack.observability_onboarding.card.customLogs.description.text',
@@ -263,6 +265,7 @@ export function Home() {
               paddingSize="m"
               display="plain"
               hasBorder
+              onClick={handleClickKubernetesSetupGuide}
             />
           </EuiFlexItem>
         </EuiFlexGroup>