[Bug]: No way to select vitest project for addon-test

[mrginglymus]

Describe the bug

I'm trying to migrate from test-runner to addon-test. I have an existing suite of tests using vitests browser mode. Whilst running tests from the cli runs fine, attempting to run from the UI results in an error:

Found multiple projects that run browser tests in headed mode: "storybook (chromium)", "default (chromium)". Vitest cannot run multiple headed browsers at the same time. Please, filter projects with --browser=name or --project=name flag or run tests with "headless: true" option.

Presumably we need a way to direct vitest to use the correct project in this block:

storybook/code/addons/test/src/node/vitest-manager.ts

Lines 92 to 103 in 81513d0

	this.vitest = await createVitest('test', {
	root: vitestWorkspaceConfig ? dirname(vitestWorkspaceConfig) : process.cwd(),
	watch: true,
	passWithNoTests: false,
	// TODO:
	// Do we want to enable Vite's default reporter?
	// The output in the terminal might be too spamy and it might be better to
	// find a way to just show errors and warnings for example
	// Otherwise it might be hard for the user to discover Storybook related logs
	reporters: ['default', new StorybookReporter(this.testManager)],
	coverage: coverageOptions,
	});

Reproduction link

https://stackblitz.com/edit/github-7znwqsbf?file=package.json

Reproduction steps

1. Run storybook in dev mode
2. Attempt to run tests via UI
3. Observe error in console

System

System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 18.20.3 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.3 - /usr/local/bin/npm <----- active
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    @storybook/addon-essentials: ^8.6.0 => 8.6.0 
    @storybook/addon-onboarding: ^8.6.0 => 8.6.0 
    @storybook/blocks: ^8.6.0 => 8.6.0 
    @storybook/experimental-addon-test: ^8.6.0 => 8.6.0 
    @storybook/react: ^8.6.0 => 8.6.0 
    @storybook/react-vite: ^8.6.0 => 8.6.0 
    @storybook/test: ^8.6.0 => 8.6.0 
    storybook: ^8.6.0 => 8.6.0

Additional context

No response