Alerts: reconcile Snooze labels and values

[ericpgreen2]

In the Create/Edit Alert form, we provide the ability to "snooze" an alert for a period of time. We define the labels & values for the various "snooze" options here.

The "Rest of X" labels do not correctly represent the underlying values. For example:

"Rest of Hour" value:

• Current: 1 hour
• Expected: the delta between the current time and the end-of-hour

"Rest of Day" value:

• Current: 24 hours
• Expected: the delta between the current time and the end-of-day

We should either change the labels to e.g. "1 hour" & "24 hours" or correctly compute the time until the end-of-period.

Reported in Slack