test: create and delete temp folder in scripts (#1869)

Author: Linchin

scripts/decrypt-secrets.sh

@@ -20,6 +20,10 @@ ROOT=$( dirname "$DIR" )
 # Work from the project root.
 cd $ROOT
 
+# Create working directory if not exists. system_tests/data is not tracked by
+# Git to prevent the secrets from being leaked online.
+mkdir -p system_tests/data
+
 gcloud kms decrypt \
   --location=global \
   --keyring=ci \

scripts/encrypt-secrets.sh

@@ -29,4 +29,6 @@ gcloud kms encrypt \
   --plaintext-file=system_tests/secrets.tar \
   --ciphertext-file=system_tests/secrets.tar.enc
 
-rm system_tests/secrets.tar
+rm system_tests/secrets.tar
+
+rm system_tests/data