Parametrize target_dir for the timestamp

The default location where we write timestamp files is
/tmp, however, this location does not work for all systems -
/tmp directory cannot be expected to persist across reboots
of an instance.

This commit allows users to set their preferred location and
override the default (/tmp) target dir.

Closes-Bug: #2051268
Change-Id: Id23ae70001525c8eb95d6baf0aca2b4d399e63a1
diff --git a/releasenotes/notes/Add-scenario-config-opt-target-dir-5a969b64be1dc718.yaml b/releasenotes/notes/Add-scenario-config-opt-target-dir-5a969b64be1dc718.yaml
new file mode 100644
index 0000000..3adacfc
--- /dev/null
+++ b/releasenotes/notes/Add-scenario-config-opt-target-dir-5a969b64be1dc718.yaml
@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    Adding a new config options `[scenario]/target_dir` which allows
+    users to specify the location where timestamps files will be
+    written to. The default value is /tmp that, however, cannot be
+    expected to persist across reboots of an instance.