Update unique_identifier retrieval instructions (#35813)

Updated PowerShell script instructions for unique identifier retrieval
based on installer scope.

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# Checklist for submitter

If some of the following don't apply, delete the relevant line.

- [ ] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
See [Changes
files](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/guides/committing-changes.md#changes-files)
for more information.

- [ ] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements)
- [ ] If paths of existing endpoints are modified without backwards
compatibility, checked the frontend/CLI for any necessary changes

## Testing

- [ ] Added/updated automated tests
- [ ] Where appropriate, [automated tests simulate multiple hosts and
test for host
isolation](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/reference/patterns-backend.md#unit-testing)
(updates to one hosts's records do not affect another)

- [ ] QA'd all new/changed functionality manually

For unreleased bug fixes in a release candidate, one of:

- [ ] Confirmed that the fix is not expected to adversely impact load
test results
- [ ] Alerted the release DRI if additional load testing is needed

## Database migrations

- [ ] Checked schema for all modified table for columns that will
auto-update timestamps during migration.
- [ ] Confirmed that updating the timestamps is acceptable, and will not
cause unwanted side effects.
- [ ] Ensured the correct collation is explicitly set for character
columns (`COLLATE utf8mb4_unicode_ci`).

## New Fleet configuration settings

- [ ] Setting(s) is/are explicitly excluded from GitOps

If you didn't check the box above, follow this checklist for
GitOps-enabled settings:

- [ ] Verified that the setting is exported via `fleetctl
generate-gitops`
- [ ] Verified the setting is documented in a separate PR to [the GitOps
documentation](https://github.com/fleetdm/fleet/blob/main/docs/Configuration/yaml-files.md#L485)
- [ ] Verified that the setting is cleared on the server if it is not
supplied in a YAML file (or that it is documented as being optional)
- [ ] Verified that any relevant UI is disabled when GitOps mode is
enabled

## fleetd/orbit/Fleet Desktop

- [ ] Verified compatibility with the latest released version of Fleet
(see [Must
rule](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/workflows/fleetd-development-and-release-strategy.md))
- [ ] If the change applies to only one platform, confirmed that
`runtime.GOOS` is used as needed to isolate changes
- [ ] Verified that fleetd runs on macOS, Linux and Windows
- [ ] Verified auto-update works from the released version of component
to the new version (see [tools/tuf/test](../tools/tuf/test/README.md))

ee/maintained-apps/README.md

@@ -52,8 +52,9 @@
 1. Find the Winget PackageIdentifier in the [winget-pkgs repo](https://github.com/microsoft/winget-pkgs).
 
 2. Get the unique identifier that Fleet will use for matching the software with software inventory:
-  - On a test Windows host, install the app manually, then run the following PowerShell script: `Get-ItemProperty 'HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*' | Where-Object {$_.DisplayName -like '*<App Name>*'} | Select-Object DisplayName, DisplayVersion, Publisher`
-  - Use the exact value from `DisplayName` as the `unique_identifier`.
+  - On a test Windows host, install the app manually, then run the following PowerShell script that correlates to the defined `installer_scope`:
+    - Machine scope: `Get-ItemProperty 'HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*' -ErrorAction SilentlyContinue | Where-Object {$_.DisplayName -like '*<App Name>*'} | Select-Object DisplayName, DisplayVersion, Publisher`
+    - User scope: `Get-ItemProperty 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*' -ErrorAction SilentlyContinue | Where-Object {$_.DisplayName -like '*<App Name>*'} | Select-Object DisplayName, DisplayVersion, Publisher`
 
 If the `unique_identifier` doesn't match the `DisplayName`, then Fleet will incorrectly create two software titles when the Fleet-maintained app is added and later installed. One title for the Fleet-maintained app and a separate title for the inventoried software.