[Bug]: V2 docs give scaling/deployment instructions for removed V1 binaries (jaeger-collector, jaeger-ingester)

### What happened?

These sections still reference the v1 architecture. Jaeger v2 replaced the standalone jaeger-collector, jaeger-query, jaeger-ingester, and jaeger-agent binaries with a single unified jaeger binary built on the OpenTelemetry Collector framework (as described in v2/_dev/_index.md). The scaling guidance (e.g. "Adding jaeger-collector instances..." and jaeger-ingester recommendations) was carried over from the v1 docs without being updated for the v2 architecture, so it can mislead users deploying or scaling Jaeger v2.

### Steps to reproduce

1.Open content/docs/v2/_dev/operations/performance-tuning.md and review the "Scale the Collector up and down" and "Consider using Kafka as intermediate buffer" sections.
2.Open content/docs/v2/_dev/faq.md and review "Do I need to run multiple collectors?".
3.Compare them with the current jaegertracing/jaeger main branch. The cmd/ directory now contains only the unified jaeger binary; the standalone jaeger-collector, jaeger-query, and jaeger-ingester binaries no longer exist.

### Expected behavior

The documentation should reflect the Jaeger v2 architecture. Instead of describing scaling around standalone jaeger-collector and jaeger-ingester binaries, it should describe scaling by running multiple instances of the unified jaeger binary and its internal collector/ingester pipelines.

I already have a fix prepared and will open a PR shortly (branch: fix/v2-docs-stale-collector-references on my fork).

### Relevant log output

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### Screenshot

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### Additional context

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### Jaeger backend version

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### SDK

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### Pipeline

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### Stogage backend

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### Operating system

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### Deployment model

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### Deployment configs

```shell

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Read content/docs/v2/_dev/operations/performance-tuning.md and content/docs/v2/_dev/faq.md, then compare the referenced architecture with v2/_dev/_index.md and the current cmd/ directory. Update the scaling and deployment guidance to match the unified v2 binary, and verify that the affected sections no longer describe removed standalone binaries.

Written by the indexing model from the issue text.