[Bug] viteDefaultClientConditions should not be applied in Vite 5 projects

[yannbf]

Feedback from EAP:

Hey. What exactly changed in the latest patch version 8.4.6 of the experimental test addon? We are now getting this, while in version 8.4.5 everything works fine. Error: require() of ES Module /path/to/myuser/project/node_modules/@fortawesome/fontawesome-svg-core/index.mjs not supported.

This is related to viteDefaultClientConditions was added in the vitest plugin in 8.4.6, here: https://github.com/storybookjs/storybook/pull/29710/files#diff-604740f662e4e19338c6063aef059bbac9f56dee9c0f378db77d98ae702c2709R111-R122

[JReinhold]

This is related to viteDefaultClientConditions was added in the vitest plugin in 8.4.6

We're not exactly sure of this, at least trying to fix it via #30055 didn't help.

Closing this because it lacks a minimal reproduction, we can open it again it if becomes relevant.