[Metricbeat][Kubernetes] Fix scheduler and proxy dashboard

[constanca-m]

What does this PR do?

Regarding #34161, some of the visualizations on Proxy and Scheduler dashboard were using kubernetes.controllermanager.* metrics leading to empty visualizations. The only change is switching those metrics to either kubernetes.scheduler.* for Scheduler dashboard and to kubernetes.proxy.* for Proxy dashboard.

Also updated the remaining area charts to line charts. Example:

A visualization like the one on the right, will be similar to the one on the left in case of a rate change.

Related issues

• Relates [Metricbeat] [Kubernetes] Fix metrics and dashboards from scheduler, proxy and controller manager #34161

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @constanca-m? 🙏.
For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
• The upcoming minor version of the Elastic Stack (if you're not pushing a breaking change)

To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v8./d.0 is the label to automatically backport to the 8./d branch. /d is the digit

[elasticmachine]

💚 Build Succeeded

the below badges are clickable and redirect to their specific view in the CI or DOCS

Expand to view the summary

Build stats

• Start Time: 2023-01-09T10:52:46.223+0000

• Duration: 54 min 46 sec

Test stats 🧪

Test	Results
Failed	0
Passed	3930
Skipped	876
Total	4806

💚 Flaky test report

Tests succeeded.

🤖 GitHub comments

Expand to view the GitHub comments

To re-run your PR in the CI, just comment with:

• /test : Re-trigger the build.

• /package : Generate the packages and run the E2E tests.

• /beats-tester : Run the installation tests with beats-tester.

• run elasticsearch-ci/docs : Re-trigger the docs validation. (use unformatted text in the comment!)