Re-name project delete "adjourned" and "soft deleted" as "delayed" in docs

Problem to solve

Delayed project deletion was introduced under #32935 (closed) under the name "soft delete". Technically it is not soft delete, because that would mean the record is permanently hidden from users (not temporarily in a different state). Internally, the delay was referred to as "adjourned" or "adjournment", which is a term that many users and developers may not understand.

Proposal

In the docs:

• Refer to "soft delete" as "delayed delete".
• Refer to "adjourned" as "delayed".
• Refer to "adjournment period" as "delay".

Out of scope

The same changes will be made to the code under #339478