Since mozglue is now aware of Gecko process-types, remove the
configurator for this bug's associated experiment. Instead, use
`GeckoProcessType` directly in mozjemalloc.
This requires a couple of adjustments for non-Firefox uses of
mozjemalloc:
- Since `logalloc-replay` uses mozjemalloc in an odd way, tweak its
`moz.build` to also include `mozglue/misc/ProcessType.cpp`.
- Since `GeckoProcessType` is not available in standalone SpiderMonkey
builds, make the mostly-arbitrarily choice to always stall there.
No functional changes.
Differential Revision: https://phabricator.services.mozilla.com/D155300
443cdd5466