shell/cahcase.sh: Move cas_found initialisation closer to usage.

Makes the code easier to read.

shell/caucase.sh

@@ -1183,7 +1183,7 @@ EOF
     # shellcheck disable=SC2039
     local netloc="$1" \
       cas_file \
-      cas_found=0 \
+      cas_found \
       csr_id \
       status \
       tmp_dir \
@@ -1296,6 +1296,7 @@ EOF
     if [ ! -d cas_crt ]; then
       _fail 'cas_crt not created\n'
     fi
+    cas_found=0
     for cas_file in cas_crt/*; do
       if [ -r "$cas_file" ] && [ ! -h "$cas_file" ]; then
         if [ "$cas_found" -eq 1 ]; then