Revert "Enable spurious test on Juno"

This reverts commit 424db295a8ee571efc92fc29c46ece28313c6b3d.

Reason for revert: The test is unstable on Juno and intermittently fails.

Change-Id: Id1b14068789a1219b1c2528e66690e7e5d8c6979
diff --git a/plat/arm/juno/juno64_tests_to_skip.txt b/plat/arm/juno/juno64_tests_to_skip.txt
index 9636021..53c7e7f 100644
--- a/plat/arm/juno/juno64_tests_to_skip.txt
+++ b/plat/arm/juno/juno64_tests_to_skip.txt
@@ -4,3 +4,5 @@
 # SPDX-License-Identifier: BSD-3-Clause
 #
 
+# The multicore spurious interrupt test is known to cause problems on Juno
+IRQ support in TSP/Multicore spurious interrupt test