Count FID = NULL as passing CWV assesment

[alekseykulikov]

According to the discussion with Annie:

If a site does not have data for FID, it is counted as passing the FID part of the assessment. It's only for FID.

There's an issue with CWV assessment script that counts only origins that have FID: https://github.com/GoogleChrome/CrUX/blob/main/sql/core-web-vitals-compliance-rates.sql#L20

Therefore, a following issue with % origins passing the CWV assessment. I recalculated with an optional FID, and in March 2021 there're 27.1% of origins that pass the CWV assessment. It's almost 3% growth (the most significant change since it's tracked).