Duplicated requests when leaving page with `hx-boost`

Some requests issued when navigating to a page (e.g. getting an image) are issued again when leaving the page by clicking on a link to navigate to another page, using `hx-boost`.

**Steps to reproduce**

- Get the files from this [Gist](https://gist.github.com/GaelGirodon/8ba17790f1b1db412e2d99fa8f806357)
- Start a local PHP development server: `php -S localhost:8000`
- Open
- Open the network inspector
- Navigate between `page1.php` and `page2.php`, multiple times, with JS/htmx enabled, then disabled

**Actual**

- _With JS/htmx_: a request to `stream.php` is issued each time (when navigating to and from `page1.php`), even if only `page1.php` has the `` tag ❌


- _Without JS/htmx_: the request to `stream.php` is only issued when navigating to `page1.php` ✔️


**Expected**

The request to `stream.php` should only be issued when navigating to (and not from) `page1.php`, in both cases.

➡️ Using `hx-boost` shouldn't trigger additional requests. Does htmx DOM manipulation is responsible for triggering these requests? On pages with many resources (multiple `` elements), this can lead to a lot of useless additional requests to be sent. Can we prevent this?

**Some more things I've tested**

- Disabling the cache doesn't seem to solve the problem (`historyCacheSize = 0`, `historyEnabled = false`)
- Using `@hotwired/turbo` (instead of htmx + `hx-boost`), with prefetch disabled (`turbo-prefetch` = `false`):
- With cache enabled (default): the same issue happens
- With cache disabled (`turbo-cache-control` = `no-cache`): the issue disappears

**Environment**

- **htmx**: 1.9.12 (from CDN or from NPM + bundled using Vite)
- **Browser**: Firefox 127, Chrome 125
- **Backend**: Go/Echo, PHP
- **OS**: Windows 11

PS: thanks for this great library!

Get the reproduction files from the linked Gist, then run `php -S localhost:8000` and compare navigation between page1.php and page2.php in the network inspector with htmx enabled and disabled. Focus on why stream.php is requested when leaving page1.php; done means navigation with hx-boost produces no additional stream.php request.

Written by the indexing model from the issue text.