Ignore missing temporary files during cleanup

Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>
diff --git a/tests/scripts/all-helpers.sh b/tests/scripts/all-helpers.sh
index d7af599..4fc8cfa 100644
--- a/tests/scripts/all-helpers.sh
+++ b/tests/scripts/all-helpers.sh
@@ -285,7 +285,7 @@
                 result=0
             fi
         fi
-        rm "$testbin"
+        rm -f "$testbin"
     fi
     return $result
 }