Fix projection queries for compatibility with Mongo DB 4.4

[Kami]

st2 execution list CLI command is failing out of the box when using MongoDB.

See two comments here for more info - #5177 (comment), #5177 (comment).

[amanda11]

@Kami Is this issue now resolved, given the #5251 merge?

[Kami]

Yep, sorry, forgot that the issue didn't auto close (forgot to reference it in the PR description).