Fix apparently wrong `delete` and `delq` value discards (bug#61730)

Fix apparently wrong `delete` and `delq` value discards (bug#61730)

* lisp/startup.el (normal-top-level):
Update process-environment in case the DISPLAY variable comes first.
Also stop iterating over initial-environment once the first DISPLAY
is found.
* lisp/allout.el (allout-get-configvar-values):
* lisp/org/org.el (org-display-inline-remove-overlay):
* lisp/progmodes/gdb-mi.el (gdb-get-location):
* lisp/progmodes/idlwave.el
(idlwave-convert-xml-clean-routine-aliases)
(idlwave-convert-xml-clean-sysvar-aliases):
* lisp/textmodes/reftex.el (reftex-ref-style-toggle):
Update the base variable after performing a destructive deletion,
where it was obvious that this was intended.