Export CSV Query Metrics Columns Missing due to absence of first user's query data

[ppratikcr7]

Version where bug was found:
"5.2"

Describe the bug
Export CSV edge case: If the first user in the CSV rows is not having any query logs data, the metrics columns wont be shown in CSV data.

Expected behavior
We should store the metrics columns irrespective of users not having query logs data.

[bcb37]

QA: all metrics columns are shown, even without data.