Fix edxapp monitors

[robrap]

This ticket captures a variety of fixes and enhancements for our edxapp monitors.

Enhancements:

• Add env to the alert title. (It looks like this happened already.)

Fixes (blocked on edxapp DD trace issue):

• For 3 search queries in Low apdex (burst) monitor, restore edge alerts by switching env:prod to env:(prod OR edge).
  • Disabling NR APM causes trace concatenation in Datadog #692 (blocks this fix)

Fixes:

• Unmute (and possibly tune) the two muted sustained monitors.
  • Document how to create DD monitor like New Relic's "alert if X is over Y for entire time period" #691 (related to this fix)
  • IP Chain monitor also flaps at times. Is this relate to the same issue, or something else?
  • [question] Once sustained monitoring is back, should we disable burst in edge? It flaps, potentially due to low volume.

Notes:

• Since there are many places where the monitor title is what is most easily viewable, and our old NR alerts were split between edge and prod, and it was easier to see the difference, it would be great to restore that. This is the reason for the enhancement idea.

[robrap]

• The sustained alerts were unmuted now that the concatenation issue was resolved.
  • If they need to be tuned, I'll leave that to be more specifically addressed or tasked.
  • There was the thought that we might need something like Document how to create DD monitor like New Relic's "alert if X is over Y for entire time period" #691 to address this.

I'm going to close this ticket, and we'll address any actual issues that arise.