default sender name to OpenFn

[taylordowns2000]

I think we should default this to "OpenFn", even though "Lightning" is the codename we've been using for OpenFn v2. This was the original request, yes, @aleksa-krolls ?

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 89.69%. Comparing base (ec9e9cd) to head (0b329bd).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2192 +/- ## ======================================= Coverage 89.69% 89.69% ======================================= Files 275 275 Lines 9036 9036 ======================================= Hits 8105 8105 Misses 931 931 ```

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