[BUG] Update Getting started to use new data prepper pipelines and index_type

[ps48]

What is the bug?
OpenSearch Dashboards Observability stills points to older pipelines and index_types. This needs to be update with clear guidelines of usage and how to get started with new Observability stack.

What is the expected behavior?
A clear and concise description of what you expected to happen.

What is your host/environment?

• OpenSearch 3.5

Do you have any screenshots?
If applicable, add screenshots to help explain your problem.

Do you have any additional context?
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[horovits]

fixing it would be great, users reported confusing guidelines between what's seen on our demo (that's based on the OpenTelemetry community demo) and what's in this page. See OpenSearch slack for reference:
https://opensearch.slack.com/archives/C052APZA1FA/p1772442191182199

[ps48]

Update: discussed with the team internally, we are planning of removing the getting started altogether in the next release. The rationale is this gets outdated often and is not in sync with code. the current documentation on stack and Opensearch.org is more updated. Targeting in 3.7. This will be part of the new left nav project initiative for Observability workspace: opensearch-project/OpenSearch-Dashboards#11545