Fill in NaNs for missing data

[adityauj]

Currently there is a visual bug where requested data is not displayed completely on the graphs. CCMS returns data for a specified interval and then frontend just renders it.

Example job:
https://monitoring.nhr.fau.de/monitoring/job/19441214

Requested Time (20 mins):

Rendered Graphs (5 mins):

Work ToDo:

1. Handle this in CCMS to return full length of data and fill it with NaNs for the missing data.