CI Build: Remove ARMClang Configs from GNU tests

ARMClang compiler is not needed in pp_test_gnu group.

Change-Id: I153f7ec507071c0e65b4cccf72646aa7bcf8f5a1
Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
diff --git a/build_helper/build_helper_configs.py b/build_helper/build_helper_configs.py
index 323d425..2324168 100755
--- a/build_helper/build_helper_configs.py
+++ b/build_helper/build_helper_configs.py
@@ -1182,8 +1182,7 @@
 config_pp_test_gnu = {"seed_params": {
                 "tfm_platform":     ["mps2/an521", "mps2/an519",
                                      "musca_b1"],
-                "toolchain_file":   ["toolchain_GNUARM.cmake",
-                                     "toolchain_ARMCLANG.cmake"],
+                "toolchain_file":   ["toolchain_GNUARM.cmake"],
                 "psa_api":          [True, False],
                 "isolation_level":  ["1", "2"],
                 "test_regression":  [True],