Add more info on informatica support, clarify escalation process

I was having trouble figuring out the point of view I should write this as (using Integration Platform Team and "we" interchangeably for example). Open to feedback if the voice/perspective was unclear.

Also, I used Integration Platform Team since it's used through our documentation, and I figured we'll have a separate effort to update it as needed since the Integration Platform Team doesn't exist anymore (changed to API Team).