rename event

[p-phung]

Describe your changes

Rename drought event as in IBF API requirement. This is to replace earlier PR as it has other irrelevant commits.

Checklist before requesting a review

• I have performed a self-review of my code
• I have added tests wherever relevant

[gulfaraz]

@p-phung this change conflicts with #21

We must investigate which naming convention to use. Resulting in,

1. Update the wiki to match the code if {climate_region_name} {season_name}_{climate_region_name} is correct
2. Update the code to match the wiki if {season_name}_{climate_region_name} is correct

I prefer to stick to the existing naming because,

1. We did significant debugging for Dev #21
2. This change is based on documentation and not a runtime error

@jannisvisser do you remember which is the correct way to name drought events?

[p-phung]

@p-phung this change conflicts with #21

That's why it felt like déja vu when working on this one