Naming is inconsistent when referring to the "global queue" and "injection queue"

[rcoh]

Version
Tokio 1.40

Description
The docs refer to a "global queue" but the metrics refer to an "injection queue."

These are actually the same thing and both names should be consistent.

In my opinion, "global" is a somewhat clearer name in this case (at least, it is less jargony) but I don't have a strong preference.

[Darksonn]

The name global queue is already used in global_queue_interval which is stable, so that's probably the one that wins.

[rcoh]

Fixed by #6918