Drop the first-logon shutdown abort that never aborted anything

FirstLogonCommands Order 1 was `shutdown -a`, and it protected nothing.

The reboot it was aimed at is the one provtool schedules when the provisioning
package is applied - and Start-BulkEnrollOrchestrator.ps1 already aborts that
itself, on the line straight after provtool returns, with its own `shutdown /a`
and the comment "Abort the reboot that the provisioning package scheduled".
Our copy runs at logon, before the orchestrator has applied the package, so at
the moment it executes there is nothing pending to abort.

The reboot that actually interrupts first-logon work is the orchestrator's own
`shutdown /r /t 0 /f` at the end of its run. That one is immediate, so it has
no pending-shutdown window for `shutdown /a` to cancel, and it is deliberate -
the Entra ID join needs it.

So the entry was a no-op that read like protection. It cost real time this week:
its presence was taken as evidence that first-logon work was being guarded when
it was not.

Removing it changes no behaviour. What it was reaching for - first-logon work
surviving a mid-logon reboot - needs resumability instead, which is what the
retired Office payload now does and what zscaler.bat still lacks.

Order 2 (zscaler) is left numbered 2; FirstLogonCommands execute in ascending
Order and gaps are legal, so renumbering would be churn for no gain.

Live gea-standard and gea-engineer updated to match. lint-unattend.py passes
clean on all three live files and both repo copies. gea-shopfloor never had
this entry.

playbook/FlatUnattendW10.xml

@@ -276,11 +276,6 @@
           <SkipMachineOOBE>false</SkipMachineOOBE>
         </OOBE>
         <FirstLogonCommands>
-            <SynchronousCommand wcm:action="add">
-                <Order>1</Order>
-                <CommandLine>shutdown -a</CommandLine>
-                <Description>Cancel any scheduled shutdown from Office installation</Description>
-            </SynchronousCommand>
             
             <!-- Install Zscaler -->
             <SynchronousCommand wcm:action="add">