Pick lower ephemeral port for browser mode

Clear and concise description of the problem

When using browser mode, Vitest picks a port starting at 63315.
I've been observing failures with some users using "corporate" windows devices. I wasn't able to diagnose in detail but it seems that some security policies might prevent users from starting servers on high ranges.

IANA seems to recommend the following range 49152-65535 for ephemeral ports, hence the 63315, I guess.

Right now, I don't know if the whole range is blocked by such policies and if it would be more pragmatic to just use a port range <10000.

I am opening this issue to collect more feedback from the trenches.

Suggested solution

Pick ports in a lower range.

Alternative

The current workaround is to override the port manually in the configuration:

{
  test: {
    browser: {
      api: 7357
    }
  }
}

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

No files or tests are named. Start by locating the browser mode port selection and its configuration handling, then investigate a lower default range and the existing manual override. Done means browser mode uses a lower default port while explicit values such as 7357 continue to work.