Use new form for T-rustdoc's {beta,stable}-{nominated,accepted} notify-Zulip triggers

[fmease]

Applies #t-rustdoc > PSA: New actions on backport notifs @ 💬.
Complements #140397.

r? @apiraino or T-triagebot

[rustbot]

triagebot.toml has been modified, there may have been changes to the review queue.

cc @davidtwco, @wesleywiser

[apiraino]

@fmease do you have privileges to push #140397 in a rollup? I guess either this patch or mine will need a rebase.

[fmease]

I'm fine either way, I can also drop the FIXME removals so you don't need to deal with it.

Re. the T-compiler PR, ofc me or you could put it into the queue since one team lead has already approved but I'm not sure if you'd like to wait for the second one, too?