docs: add contributor security user namespace instructions

[MikeMcC399]

• relates to issue yarn start FATAL:setuid_sandbox_host for contributors on ubuntu 24.04 #29422

Additional details

Issue

Executing yarn start on Ubuntu 24.04 as described in the CONTRIBUTING > Getting Started section results in an error message similar to the following:

$ cypress open --dev --global
[9406:0427/165943.833191:FATAL:setuid_sandbox_host.cc(158)] The SUID sandbox helper binary was found, but is not configured correctly. Rather than run without sandboxing I'm aborting now. You need to make sure that /home/mike/cypress/packages/electron/dist/Cypress/chrome-sandbox is owned by root and has mode 4755.

The Ubuntu 24.04 Release notes > Unprivileged user namespace restrictions section describes the breaking change in security rules which causes this issue.

Change

Add a paragraph to CONTRIBUTING > Requirements for Ubuntu 24.04 linking to Ubuntu 24.04 Release notes > Unprivileged user namespace restrictions describing how to disable the user namespace restrictions for the entire system as a workaround for the issue.

This may or may not be the long-term solution.

Steps to test

Follow the instructions in Ubuntu 24.04 Release notes > Unprivileged user namespace restrictions and run yarn start on Ubuntu 24.04.

How has the user experience changed?

Contributors will be able to run Cypress after building from source on Ubuntu 24.04.

PR Tasks

• [na] Have tests been added/updated?
• [na] Has a PR for user-facing changes been opened in cypress-documentation?
• [na] Have API changes been updated in the type definitions?

cc: @AtofStryker

[cypress-app-bot]

• Create a Draft Pull Request if your PR is not ready for review. Mark the PR as Ready for Review when you're ready for a Cypress team member to review the PR.