Use Promise.halt instead of unresolved promises

[w33ble]

There are a handful of spots in Kibana where unresolved promises are used to stop the execution chain. The concern is that these promises are never garbage collected, so they present a memory leak issue.

In #3014, Promise.halt() was introduced, which will simply keep a single unresolved promise around, which will be the only promise that isn't garbage collected. Since then and catch are overridden in this new promise, the chain should not build up, and old parts of the chain should be garbage collected.

tl;dr unused, unresolved promises should be replaced with Promise.halt.

[timroes]

It looks to me that this issue is outdated, since we are trying to move nowadays to Vanilla JS promises, and not have any tight to a specific (e.g. Angular) implementation of promises.

I'll close this, but feel free to reopen, if it is still relevant.

[nreese]

@timroes I am trying to de-angularize some code that is using Promise.halt. What should I use in its place?