[DOCS-7217/7054] Add OP landing and use case docs

[maycmlee]

What does this PR do? What is the motivation?

Merge instructions

• [ ] Please merge after reviewing

Additional notes

[github-actions[bot]]

Preview links (active after the build_preview check completes)

New or renamed files

• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/archive_logs/
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/archive_logs/datadog_agent
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/archive_logs/splunk_hec
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/archive_logs/splunk_tcp
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/archive_logs/sumo_logic_hosted_collector
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/best_practice_for_scaling_observability_pipelines
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/dual_ship_logs/
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/dual_ship_logs/datadog_agent
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/dual_ship_logs/splunk_hec
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/dual_ship_logs/splunk_tcp
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/dual_ship_logs/sumo_logic_hosted_collector
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/log_volume_control/
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/log_volume_control/splunk_hec
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/log_volume_control/splunk_tcp
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/log_volume_control/sumo_logic_hosted_collector
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/sensitive_data_redaction/
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/sensitive_data_redaction/datadog_agent
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/sensitive_data_redaction/splunk_hec
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/sensitive_data_redaction/splunk_tcp
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/sensitive_data_redaction/sumo_logic_hosted_collector
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/split_logs/
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/split_logs/datadog_agent
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/split_logs/splunk_hec
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/split_logs/splunk_tcp
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/split_logs/sumo_logic_hosted_collector
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/update_existing_pipelines

Modified Files

• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/agent/remote_config/
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/legacy/
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/legacy/architecture/
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/legacy/production_deployment_overview
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/legacy/setup/
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/legacy/setup/datadog
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/legacy/setup/datadog_with_archiving
• https://docs-staging.datadoghq.com/may/op-2.0-use-cases/observability_pipelines/legacy/setup/splunk