Writing training output to HDFS fails with 'Pathname [path] is not a valid DFS filename.'

[MarkPundurs]

Describe the bug Writing training output to HDFS fails with 'Pathname [path] is not a valid DFS filename.'

To Reproduce Steps to reproduce the behavior:

1. Select a dataset.
2. Click the forecast plugin.
3. Select the training option (number 1).
4. Select an HDFS connection for the metrics dataset.

Expected behavior Plugin writes output to specified locations.

Root cause HDFS doesn't allow colons in paths: https://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-common/filesystem/model.html#Paths_and_Path_Elements

Suggested fix In dss-plugin-timeseries-forecast/custom-recipes/timeseries-forecast-1-train-evaluate/recipe.py, change line 29 from session_name = datetime.utcnow().isoformat() + "Z" to session_name = datetime.utcnow().isoformat().replace(':', '.') + "Z"