Trouble building instantsearch.js from source

### 🐛 Current behavior

When trying to build `instantsearch.js` from source, I get a different and broken result compared to the one located at https://cdn.jsdelivr.net/npm/instantsearch.js@4

(diff produced with delta)

### 🔍 Steps to reproduce

```sh
git clone git@github.com:algolia/instantsearch.git
cd instantsearch/
yarn install
cd packages/instantsearch.js
yarn build:umd
```

```
wget https://cdn.jsdelivr.net/npm/instantsearch.js@4
diff instantsearch.js@4 dist/instantsearch.production.min.js
```

(the reproduction link is empty* because it shouldn't be relevant for this bug)

### Live reproduction

https://example.com/

### 💭 Expected behavior

I'd expect to get the same output, or at least a working version.
I also tried building with the latest instantsearch.js tag, but that produced the same non working result.

### Package version

gituhub.com/algolia/instantsearch.git/master

### Operating system

Linux-NixOS 24.05

### Browser

Mozilla Firefox 128.0.2

### Code of Conduct

- [X] I agree to follow this project's Code of Conduct

The issue mentions packages/instantsearch.js, yarn build:umd, and dist/instantsearch.production.min.js; start by reproducing the build and comparing that output with the jsDelivr instantsearch.js@4 file. Done means the source build produces a working result matching the CDN artifact.

Written by the indexing model from the issue text.