[Logs onboarding] Landing page style changed (#161542)

Relates to #159655.

### Changes

This PR include the following changes:

- [x] Update the copy in the page subtitle with “Select your method for
collecting data into Observability.”
- [x] Remove badges (Quickstart, in a few minutes, setup guide,
integrations, sample data) from all cards
- [x] Remove ‘skip for now’ link
- [x] Change system logs card title with “Stream host system logs” and
card description with “The quickest path to onboard log data from your
own machine or server.”
- [x] Add system icon to system logs card
- [x] Change custom logs card title with “Stream log files” and card
description with “Stream any logs into Elastic in a simple way and
explore their data.”
- [x] Add logging icon to stream logs card 
- [x] Remove horizontal line below the cards’ title
- [x] Add “Elastic agent” badge to system logs card and stream log files
- [x] Change CTA button text with ‘Get started’ of both system logs and
stream log files card.
- [x] Remove the cards shadow and add 1px stroke Core/lightShade
- [x] Add 2px stroke Text/accentText around system logs card +
Quickstart badge on top of the card
- [x] Remove ‘sample data’ card
- [x] Change APM card title with “Collect application performance data”
and description with “Collect traces, logs, and metrics from
OpenTelemetry or APM custom agent.”
- [x] Add secondary CTA button to APM card with the text “Get started”
that links to the current flow
- [x] Add Elastic APM logo and Open Telemetry logo to APM card
- [x] Change Kubernetes card title with “Collect Kubernetes clusters
data” and description with “Collect logs and metrics from Kubernetes
clusters with Elastic agent.”
- [x] Add Kubernetes logo to Kubernetes card that links to the current
setup guide
- [x] Add secondary CTA button to Kubernetes card with the text “Get
started”
- [x] Create custom card for integrations with logs from: Amazon
Kinesis, AWS, Apache, Nginx, Google Cloud Platform, Azure and card title
“Explore 300+ ways of ingesting data with our integrations”
- [x] Add secondary CTA button to Integrations card with the text “Start
exploring” that links to the Integrations page with ‘logs’ in the search
bar
- [x] Add quick links to Integrations card to Use sample data (link to
actual flow) + Upload file (link to actual flow) + AWS Firehose (link to
docs:
https://www.elastic.co/guide/en/kinesis/current/aws-firehose-setup-guide.html)

### Missing
- [ ] Link ‘Get started’ button from Stream log files directly to the
stream log files onboarding flow (remove the select logs step)

This will be addressed in a follow up Pr since it's depending on
#159500.

### Screenshots

#### Before
<img width="2222" alt="image"
src="https://github.com/elastic/kibana/assets/1313018/d9120656-7357-4bf0-b8c8-6ce1a85e731c">

#### After
<img width="2225" alt="image"
src="https://github.com/elastic/kibana/assets/1313018/83275710-c9eb-45ac-a3b3-42ca4debf9a6">

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

@@ -61,7 +61,10 @@ function AnimatedTransitionsWizard() {
       <EuiFlexGroup direction="column" alignItems="center">
         <EuiFlexItem grow={false}>
           <EuiSpacer size="l" />
-          <EuiTitle size="l">
+          <EuiTitle
+            size="l"
+            data-test-subj="obltOnboardingStreamLogFilePageHeader"
+          >
             <h1>
               {i18n.translate(
                 'xpack.observability_onboarding.title.collectCustomLogs',