HTML Report renderer incorrect labels for custom throttling & device

#### Provide the steps to reproduce
1. Configure lighthouse to run with custom throttling settings, mark the throttling method as `devtools`, mark the `emulatedFormFactor` as "none"
2. Run LH on [any url]
3. Load the report JSON into lighthouse-viewer

#### What is the current behaviour?
* The network throttling summary is hardcoded to "Throttled Slow 4G network"
* The device summary is hardcoded to "No emulation"
* The device summary, is technically correct (emulated form factor set to none), but the other configuration options for `emulatedFormFactor` (`mobile`, `desktop`) will result in a hardcoded value of either "Emulated Nexus 5X" or "Emulated Desktop"

#### What is the expected behaviour?
* Network throttling summary should describe the network settings used
* Device summary should describe the device used

#### Environment Information
* Affected Channels: Node
* Lighthouse version: 4.0.0
* Node.js version: 11
* Operating System: All

Reference: `renderer/util.js#getEmulationDescriptions` ([Link](https://github.com/GoogleChrome/lighthouse/blob/master/lighthouse-core/report/html/renderer/util.js#L392-L440))