Index.html is produced locally when outputPath is a remote folder

### UPDATE 2020-12-20: I discovered this morning that the index.html files ARE being produced, but they are being pushed to my local machine instead of the remove machine.

From my angular.json: `"outputPath": "\\\\remote-computer-name\\all-projects-folder\\project-folder"`

Files SHOULD be copying to C:\all-projects-folder\project-folder. on the REMOTE machine. Instead, files are copying to C:\remote-computer-name\all-projects-folder\project-folder on my LOCAL machine

# 🐞 Bug report

### Command (mark with an `x`)

- [ ] new
- [x] build
- [ ] serve
- [ ] test
- [ ] e2e
- [ ] generate
- [ ] add
- [ ] update
- [ ] lint
- [ ] extract-i18n
- [ ] run
- [ ] config
- [ ] help
- [ ] version
- [ ] doc

### Is this a regression?

No. Discovered in 9.1.7. Updated to latest hoping to fix the problem. Still exists.

### Description

Title says it all. When run ng build, everything works as expected. When I run ng build --configuration=remote-build, the build completes without errors and all files are pushed to the remote folder EXCEPT index.html.

## 🔬 Minimal Reproduction

Link to repro project here: https://github.com/joshorvis/remote-build. (Only change from the default ng new is a new target added in angular.json)

1) set up a folder you can access on another machine. confirm file permissions aren't blocking writes from your local machine.
2) npm install project on local machine. Update angular.json line 86 with the network path to your remote folder.
3) run ng build. See index.html in local project folder /dist/remote-build
4) run ng build --configuration=remote-build. See everything but index.html
5) cry with me.

UPDATE: It appears that mapping the remote folder to a network drive letter will produce the index.html as expected.