Fix Windows E2E uninstall script path (#47976)

**Related issue:** #47725 moved the script but didn't update the
workflow

# Checklist for submitter

- [x] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
  N/A - CI-only change, no user-visible impact.

- [x] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements), JS
inline code is prevented especially for url redirects, and untrusted
data interpolated into shell scripts/commands is validated against shell
metacharacters.
- [x] Timeouts are implemented and retries are limited to avoid infinite
loops

## Testing

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

**How this was tested:**

1. Confirmed `uninstall-fleetd-windows.ps1` does not exist at the old
path (`it-and-security/lib/windows/scripts/`) on `main` -- reproduces
the `CommandNotFoundException`.
2. Confirmed the file exists at the new path
(`docs/solutions/windows/scripts/`).
3. Ran sparse-checkout simulations locally: old path yields no script
file, new path successfully pulls it.
4. Compared old vs new script -- the new version adds an MDM
unenrollment step that is a no-op in E2E (no MDM enrolled), so behavior
is equivalent.
5. Triggered the full E2E agent workflow on this PR branch to verify all
32 Windows jobs pass the "Uninstall Orbit" step.

## Root cause

PR #47725 ("Fix unenroll Windows instructions", merged June 19) moved
`uninstall-fleetd-windows.ps1` from
`it-and-security/lib/windows/scripts/` to
`docs/solutions/windows/scripts/` as part of merging the "turn off MDM"
and "uninstall fleetd" scripts into one. However,
`.github/workflows/e2e-agent.yml` was not updated to reflect the new
path.

This broke all 32 Windows E2E jobs (windows-2025 and windows-11-arm, all
channel/update combinations) at the "Uninstall Orbit" step. The nightly
run has been failing for 2 consecutive cycles (June 20 and 21),
exhausting all 4 retry attempts each time.

## Fix

Update the sparse-checkout path and PowerShell run command in
`e2e-agent.yml` to the new location.

## Note: inconsistent uninstall script locations

After #47725, the uninstall scripts are now in different directories per
OS:

| OS | Uninstall script location |
|---|---|
| macOS | `it-and-security/lib/macos/scripts/uninstall-fleetd-macos.sh`
|
| Linux | `it-and-security/lib/linux/scripts/uninstall-fleetd-linux.sh`
|
| Windows |
`docs/solutions/windows/scripts/uninstall-fleetd-windows.ps1` |

macOS and Linux remain in `it-and-security/lib/` (Fleet's dogfooding
GitOps config). Windows was moved to `docs/solutions/` (user-facing
documentation). This inconsistency may warrant a follow-up to decide on
a canonical location.

.github/workflows/e2e-agent.yml

@@ -518,13 +518,13 @@ jobs:
       with:
         fetch-depth: 1
         sparse-checkout: |
-          it-and-security/lib/windows/scripts/uninstall-fleetd-windows.ps1
+          docs/solutions/windows/scripts/uninstall-fleetd-windows.ps1
         persist-credentials: false
 
     - name: Uninstall Orbit
       shell: powershell
       run: |
-        .\it-and-security\lib\windows\scripts\uninstall-fleetd-windows.ps1
+        .\docs\solutions\windows\scripts\uninstall-fleetd-windows.ps1
 
   summary:
     needs: [fleetd-macos, fleetd-ubuntu, fleetd-windows]