editor: use "in a moment", not "momentarily", on interstitial

Will Thompson requested to merge wjt/gnome-builder:momentarily into master

https://en.wiktionary.org/wiki/momentarily#Usage_notes says:

Many speakers object to the use of momentarily in the sense of “in a moment” rather than “for a moment”, since this is inconsistent with the meaning of momentary […]. In place of momentarily, many speakers prefer […] the phrase “in a moment”.

I'm generally not a prescriptivist but I feel a tiny cut in my soul every time I open Builder and see this sentence.

Merge request reports