[APM Go] fix and clarify dd-trace-go v2 docs for release

[hannahkm]

What does this PR do? What is the motivation?

To minimize confusion with the differences between v1 and v2, we clarify when there are not significant changes to the specific product and link customers to the migration guide whenever possible.

Also see profiling changes here.

• Add reusable snippet to link users to migration guide. This will ease maintenance burden too.
• Swap order of v1 and v2 tabs--put v2 first.
• Remove mention of v2 in Preview.
• Add GA date to support table (subject to change).
• Refine migration guide to include more context. Preview
• TODO: Swap v2 code statements to come first OR remove v1 import statements entirely.

Merge instructions

Merge whenever possible, preferably before or around the dd-trace-go v2 GA release.

Merge readiness:

• Ready for merge

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Additional notes

[github-actions]

Preview links (active after the build_preview check completes)

Modified Files

• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/containers/amazon_ecs/apm
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/containers/docker/apm
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/data_streams/go
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/database_monitoring/connect_dbm_and_apm
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/opentelemetry/instrument/instrumentation_libraries
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/security/application_security/threats/add-user-info
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/security/application_security/threats/setup/compatibility/go
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/security/application_security/threats/setup/threat_detection/go
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/security/application_security/troubleshooting
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/security/code_security/software_composition_analysis/setup_runtime/compatibility/go
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/serverless/aws_lambda/installation/go
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/serverless/guide/datadog_forwarder_go
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/faq/trace_sampling_and_storage
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/guide/instrument_custom_method
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/guide/tutorial-enable-go-aws-ecs-ec2
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/guide/tutorial-enable-go-aws-ecs-fargate
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/guide/tutorial-enable-go-containers
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/guide/tutorial-enable-go-host
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/legacy_app_analytics/
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/other_telemetry/connect_logs_and_traces/go
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/trace_collection/compatibility/go
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/trace_collection/custom_instrumentation/go/dd-api
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/trace_collection/custom_instrumentation/go/otel
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/trace_collection/library_config/go
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/trace_pipeline/ingestion_mechanisms
• https://docs-staging.datadoghq.com/hannahkm/clarify-v2-docs/tracing/troubleshooting/tracer_debug_logs

[hannahkm]

Most important to review here is whether statements left under DSM and OTel files are accurate; has v2 made significant changes to their APIs? I don't think it has, but I'd like to confirm this.