prism: mark as failing CI

Inside docker, the installer fails with

CustomAction +PrismSearchPlugin.dll.x64 returned actual error code
-2147024770 (note this may not be 100% accurate if translation happened
    inside sandbox)
MSI (s) (18:40) [13:20:35:946]: Product: GraphPad Prism 10.4.1.627 --
Error 1904. Module C:\Program
Files\GraphPad\Prism\PrismSearchPlugin64.dll failed to register.
HRESULT -2147024770.  Contact your support personnel.

but the installation is confirmed to behave correctly outside of docker.

packages/prism.xml

@@ -2,8 +2,10 @@
 <packages:packages xmlns:packages="http://www.wpkg.org/packages">
   <package id="prism" name="GraphPad Prism" revision="%version%.1" priority="0" reboot="false">
 
+    <!-- installer fails registering PrismSearchPlugin64.dll when run inside docker -->
+    <variable name="GIT_CITEST" value="broken" />
+    <!-- Taken from searchreg.vbs DisplayName. N.B. different than DisplayVersion -->
     <variable name="version" value="10.4.1.627" />
-    <!--Taken from searchreg.vbs DisplayName. N.B. different than DisplayVersion-->	  
 
     <check type="uninstall" condition="exists" path="GraphPad Prism %version%" />