shift info push notification tweaks

[Dieterbe]

can we tweak the design of the upcoming shift notification to say something like:

You're going on call in <time>
Schedule primary, 10:00 – 22:00

for comparison, google calendar notification:

version v1.2.31

[raphael-batte]

Text suggestion:

Your on-call shift starts in 10 min Schedule primary, 10:00 – 22:00

[Matvey-Kuk]

Closing because OnCall version & labeling is missing.