memoryIdx.UpdateArchive leads to pointers in m.defById and m.defByTagSet getting out of sync

[woodsaj]

memoryIdx.Add() has a comment explaining that the pointers in defById and defByTagSet need to be the same for the same metricDefinition.

// Even if there are no tags, index at least "name". It's important to use the definition
// in the archive pointer that we add to defById, because the pointers must reference the
// same underlying object in m.defById and m.defByTagSet

see: #1303

However, memoryIdx.UpdateArchive() updates what m.defById points to without also updating m.defByTagSet

[woodsaj]

this was fixed in #1365