Remove ARM as a target for CI runs.

Author: apop5

.azurepipelines/Ubuntu-GCC5.yml

@@ -15,7 +15,7 @@
 ##
 
 variables:
-- group: architectures-arm-64-x86-64
+- group: architectures-arm64-x86-64
 - group: tool-chain-ubuntu-gcc
 - group: coverage