tests: Don't use loader.secure=no with firmware autoselection

This currently has not effect whatsoever, so it's just cluttering
the input files.

We're going to add specific handling for this scenario, as well
as a test case covering it, in an upcoming commit.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

tests/qemuxml2argvdata/firmware-auto-bios.xml

@@ -5,7 +5,6 @@
   <vcpu placement='static'>1</vcpu>
   <os firmware='bios'>
     <type arch='x86_64' machine='pc-q35-4.0'>hvm</type>
-    <loader secure='no'/>
   </os>
   <features>
     <acpi/>

tests/qemuxml2argvdata/firmware-auto-efi.xml

@@ -5,7 +5,6 @@
   <vcpu placement='static'>1</vcpu>
   <os firmware='efi'>
     <type arch='x86_64' machine='pc-q35-4.0'>hvm</type>
-    <loader secure='no'/>
   </os>
   <features>
     <acpi/>

tests/qemuxml2xmloutdata/firmware-auto-bios.x86_64-latest.xml

@@ -6,7 +6,6 @@
   <vcpu placement='static'>1</vcpu>
   <os firmware='bios'>
     <type arch='x86_64' machine='pc-q35-4.0'>hvm</type>
-    <loader secure='no'/>
     <boot dev='hd'/>
   </os>
   <features>

tests/qemuxml2xmloutdata/firmware-auto-efi.x86_64-latest.xml

@@ -6,7 +6,6 @@
   <vcpu placement='static'>1</vcpu>
   <os firmware='efi'>
     <type arch='x86_64' machine='pc-q35-4.0'>hvm</type>
-    <loader secure='no'/>
     <boot dev='hd'/>
   </os>
   <features>