fix(build): use WiX 4/5 attribute syntax for Component Condition

The WXS template declared xmlns="http://wixtoolset.org/schemas/v4/wxs"
but used WiX 3 syntax (<Condition>SOMEPROP</Condition> as a child of
<Component>). WiX 4 and later expect the condition as a Component
attribute. The build now fails with `WIX0005: The Component element
contains an unexpected child element 'Condition'`. Move the
ICINGA2_SERVICE_FOUND check from a child element to an attribute.

Validated against the v2.2.1 WXS, which used the same nested Directory
structure and Component-with-only-ServiceControl pattern successfully.
The Property/RegistrySearch addition from the October 2025 rewrite uses
standard WiX 4/5 syntax and stays.

Author: markuslf

build/create-wxs.sh

@@ -37,8 +37,7 @@ cat > "$LFMP_DIR_PACKAGED/in/lfmp.wxs" << EOF
             <Files Include="$LFMP_DIR_COMPILED\check-plugins\**" />
 
             <!-- Only run ServiceControl if the Icinga 2 service exists -->
-            <Component Id="Icinga2ServiceControl" Guid="{7e398e63-b894-47d1-9375-eea744988032}">
-              <Condition>ICINGA2_SERVICE_FOUND</Condition>
+            <Component Id="Icinga2ServiceControl" Guid="{7e398e63-b894-47d1-9375-eea744988032}" Condition="ICINGA2_SERVICE_FOUND">
               <ServiceControl
                   Id="icinga2"
                   Name="icinga2"