Make SV status reports less noisy part I

[julientinguely-da]

fixes https://github.com/DACH-NY/canton-network-internal/issues/2384

three main requirements:

• Separate alerts for our SVs and other SVs
• Set the threshold for other SVs to 15 minutes
• For our SVs, have a separate threshold for slack (5 minutes) and emails (15 minutes)

tested on scratchb with tmp-canton-network-deployments slack channel and own email, where the external SVs are the -eng SVs here.

notifications policies:

overview of the new alerts:

Click to see the alert configuration details

internal SVs 5min slack alert:

internal SVs 15min email alert:

external SVs 15mins slack + email alert:

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[isegall-da]

Nice, thank you