Fix blocking call in FindByEmailAsync

[cremor]

Make FindByEmailAsync actually an async method.

Description

Seems like it was initially changed to a sync call as a workaround in #10660 by @ajcvickers. A part of the workaround was later removed in #11336 (again by @ajcvickers), but it stayed a sync call. Even later UserStore.FindByEmailAsync was made async again in #24116 (for #24113) by @HaoK, but the UserOnlyStore was not fixed.

Fixes #43973

[ghost]

Thanks for your PR, @cremor. Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[WeihanLi]

LGTM

[ghost]

Looks like this PR hasn't been active for some time and the codebase could have been changed in the meantime.
To make sure no conflicting changes have occurred, please rerun validation before merging. You can do this by leaving an /azp run comment here (requires commit rights), or by simply closing and reopening.

[cremor]

/azp run

[azure-pipelines]

Commenter does not have sufficient privileges for PR 50603 in repo dotnet/aspnetcore

[cremor]

Commenter does not have sufficient privileges for PR 50603 in repo dotnet/aspnetcore

Great. How do I keep my own PR open?

@halter73 Could you please review?

[martincostello]

or by simply closing and reopening.

[halter73]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[halter73]

Thanks!

[ghost]

Hi @cakescience. It looks like you just commented on a closed PR. The team will most probably miss it. If you'd like to bring something important up to their attention, consider filing a new issue and add enough details to build context.