Add explicit test for file not found

...caching the metadata moved where ParquetTable did I/O,
which introduced a segfault on not found

tests/test-all

@@ -4,6 +4,7 @@ set -euo pipefail
 here=$(dirname "${BASH_SOURCE[0]}")
 
 set -x
+"$here"/test-non-existent
 "$here"/test-unsupported
 "$here"/test-supported
 "$here"/test-queries