Update Performix Learning Paths and remove stale Sysreport MCP references

[sairamvarmabudharaju]

Summary

• migrate five Performix Learning Paths from Arm MCP routing to the dedicated Arm Performix MCP server and current recipe workflows
• remove obsolete apx_recipe_run references and stale SSH key and known_hosts mounts from six installation guides
• remove the retired sysreport_instructions tool section and stale MCP tool-list references
• direct host architecture, CPU, memory, and hardware questions through knowledge_base_search and the existing Sysreport Learning Path
• remove superseded Performix setup images and tighten prompt and tool guidance

Sysreport-specific updates

• update the Arm MCP Server overview and migration prompt
• update the Docker MCP Toolkit, Antigravity, and Gemini tool examples
• keep the actual Sysreport Learning Path unchanged

Validation

• rendered and reviewed all affected Learning Paths and installation guides locally
• confirmed no stale apx_recipe_run, sysreport_instructions, arm-mcp/sysreport, SSH-key mount, known_hosts mount, or deleted-image references remain under content
• ran git diff --check upstream/main...origin/update-performix-mcp-references
• verified the combined branch contains 11 commits and 27 unique changed files
• verified the combined branch can merge cleanly with current upstream/main

Contributor checklist

This PR updates existing Learning Paths; it does not create a new Learning Path.

• I have reviewed Create a Learning Path (not applicable)

Please do not include any confidential information in your contribution. This includes confidential microarchitecture details and unannounced product information.

• I have checked my contribution for confidential information

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution under the terms of the Creative Commons Attribution 4.0 International License.