use a single-use temp name for integration test dir

Author: 6293

integration_test/run.sh

@@ -1,6 +1,7 @@
 #!/bin/sh
 
-TESTDIR=/tmp/rust_miniscript_test
+RAND_DIR=$(cat /dev/urandom | xxd | fold -w 5 | head -n 1)
+TESTDIR=/tmp/"rust_miniscript_test_$RAND_DIR"
 
 rm -rf ${TESTDIR}
 mkdir -p ${TESTDIR}/1