Alerting: Fixing mobile notifications in Microsoft Teams

[manacker]

Apparently the summary field in a Microsoft Teams webhook request field gets used for the text displayed in mobile push notifications. If that field contains only whitespace the push notification displays the nonsensical text

Card - access it on https://go.skype.com/cards.unsupported

Therefore this commit mirrors the notification title in the summary field.
It also removes the unsupported fields Mention and Recipient from the notifier data struct.

[codecov-io]

Codecov Report

Merging #11484 into master will decrease coverage by 0.04%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master   #11484      +/-   ##
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- Coverage    51.9%   51.85%   -0.05%     
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  Files         359      359              
  Lines       26066    26058       -8     
  Branches     1509     1508       -1     
==========================================
- Hits        13530    13513      -17     
- Misses      11796    11803       +7     
- Partials      740      742       +2

[torkelo]

looks strange to have summary and title be the same (Is title shown in mobile notifications), should summary not use message when there is a message and some fallback like "NA" when no message (so no empty string). Is summary used in other clients?

[manacker]

Summary and title seem to be used in different contexts:

Summary seems to be used for the activity feed and notifications, while title is used to render the actual chat message.
Here are the iOS notifications top is with empty summary, bottom with a non-empty summary.

Hence I think mirroring the title is better than giving no summary at all.

[manacker]

@torkelo Do you need anything else from me to get this PR merged?

[marefr]

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