Cleanup Network Handling in Gatherers

**Summary**
The root cause of https://github.com/GoogleChrome/lighthouse/issues/11450 was that we link up network records and image elements using `record.url === image.src` but this breaks down for images that redirected. I looked around and it seems like many, many audits might be susceptible to a similar pitfall.

A few more things that came to mind we should probably fix in this space...

- [ ] Extract a shared `findMatchingNetworkRecord` function that can handle this redirect logic, do the `*ByUrl` nonsense that we have duplicated everywhere, etc
- [x] Remove duplicated `resourceSize` in `ImageElements` that duplicates network record property (breaking change, ref https://github.com/GoogleChrome/lighthouse/issues/11207)
- [ ] Check the redirect URL reporting behavior of...
- [ ] ScriptElements
- [ ] CSSUsage
- [ ] JsUsage

i.e. when we create our map of URL -> network record we shouldn't just use URL, but also use..
```js
// Also index all of its redirect source.
let originalRequest = record;
while (originalRequest.redirectSource) originalRequest = originalRequest.redirectSource;
map[originalRequest.url] = record;
```

Start by locating the duplicated network-record URL matching and *ByUrl logic, then inspect the ScriptElements, CSSUsage, and JsUsage reporting paths. Verify how redirectSource chains are represented and where URL-to-record maps are built. Done means shared redirect-aware matching is used consistently and redirect URL behavior is checked for all three areas.

Written by the indexing model from the issue text.