Arm backend: Remove arm_test folder build and test output from git radar

This adds the arm_test folder used as default build and test output
by the arm scripts to .gitignore

Signed-off-by: Zingo Andersen <[email protected]>
Change-Id: Ica94744136167afd904205a30eadf34cc3098ca6

Author: zingo

.gitignore

@@ -8,6 +8,7 @@ cmake-android-out/
 cmake-out-android/
 cmake-ios-out/
 ethos-u-scratch/
+arm_test/
 executorch.egg-info
 pip-out/
 __pycache__/