We are eager to enable server targets in 92 as it can fix a couple of edgecases when enabling fission.
At the same time, we are a bit late in the release cycle and as this mode impact both fission and non-fission we might reduce the risk by only enabling this codepath when fission is enabled. And that's where it is the most useful.

This may also help landing the pref flip in bug 1702715 as we would most likely only impact browser mochitest with fission enabled. xpcshell, mochitest chrome and test disabled on fission won't trigger this code.

Once we branch in two weeks for Fx93 we can then try to enable this for non-fission.

(I'll be using bug 1639934 as a template on how to implement this)

This helps keeping the existing preference for toggling server targets without fission.
Otherwise we might have kept the existing, which would only toggle when fission is ON...
But it might then be harder to adapt currently toggling this pref.
Some expect to have it working even without fission.

I went over tests which were setting the pref to disable server targets.

We ended up enabling server side targets on all configuration.
So we are going to drop this patch.
We could have tried to uplift this to 92, but that sounds like a very time consuming which reduce the quality of 93.