Terminal overwriting hard link to settings.json

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### Windows Terminal version

1.15.3465.0

### Windows build number

10.0.19045.2546

### Other Software

_No response_

### Steps to reproduce

Replacing settings.json with a hard link to an existing settings file while the terminal is running causes weird behavior. The hard link is broken shortly after it is created. Then it looks like the previous settings file and newly linked file are merged and written out as a new, unlinked, combined settings file.

I ran into this accidentally because the quake window was still open and I didn't realize it.

Repro:
* Open terminal
* `New-Item -ItemType HardLink -Force -Path settings.json -Target my-synced-settings.json`
* `(Get-Item settings.json).LinkType -eq "HardLink"` is true
* `Start-Sleep -Milliseconds 1000`
* `(Get-Item settings.json).LinkType -eq "HardLink"` is now false

But if you do it a second time it works
* `New-Item -ItemType HardLink -Force -Path settings.json -Target my-synced-settings.json`
* * `(Get-Item settings.json).LinkType -eq "HardLink"` is true
* `Start-Sleep -Milliseconds 1000`
* `(Get-Item settings.json).LinkType -eq "HardLink"` is true

Obviously I should be killing terminal processes before doing this, so maybe it's a bit moot. The terminal seems to respect a hard link just fine if it's already there when it starts up. Still the nuke-and-merge behavior is certainly surprising.

### Expected Behavior

If a new settings.json is copied over the existing one the terminal should not merge with or overwrite it.

### Actual Behavior

If a new settings.json is copied over the existing one the terminal overwrites it with a merged copy

Start by reproducing the hard-link behavior with settings.json and my-synced-settings.json while the terminal is running. Trace the settings.json replacement and merge behavior, then verify that replacing the file does not break the hard link or overwrite it with a merged copy.

Written by the indexing model from the issue text.