testProxy breaks axios with Basic Auth

### Link to the code that reproduces this issue https://github.com/jokklan/nextjs-reproduce-app ### To Reproduce 1. Call any endpoint with [axios](https://github.com/axios/axios) including basic auth credentials in the `auth` options key (this works) 2. Change `experimental.testProxy` to true in next.config.ts 3. Make the same axios request as in step 1, now it fails with "Request cannot be constructed from a URL that includes credential: https://user:pass@domain/path" ### Current vs. Expected behavior Changing `testProxy` should not change the behaviour of axios request. ### Provide environment information ```bash Operating System: Platform: darwin Arch: arm64 Version: Darwin Kernel Version 24.4.0: Fri Apr 11 18:32:50 PDT 2025; root:xnu-11417.101.15~117/RELEASE_ARM64_T6041 Available memory (MB): 24576 Available CPU cores: 12 Binaries: Node: 22.16.0 npm: 10.9.2 Yarn: N/A pnpm: N/A Relevant Packages: next: 15.4.2-canary.44 // Latest available version is detected (15.4.2-canary.44). eslint-config-next: N/A react: 19.1.1 react-dom: 19.1.1 typescript: 5.9.2 Next.js Config: output: N/A ``` ### Which area(s) are affected? (Select all that apply) Runtime ### Which stage(s) are affected? (Select all that apply) next dev (local) ### Additional context Changing the axios adapter to `fetch` is a temporary fix for this issue, it only happens when using the `http` adapter which is default for node requests.