[report-utilities] deprecate gnc:acccounts-get-all-subaccounts

* this function has a typo in name
* all uses of accounts-get-all-subaccounts were followed by appending
the result to the original accounts list. we have already rewritten to
use the better function in previous commit. this is now obsolete.
* inline its last use, omit sorting. list is sorted anyway afterwards.

gnucash/report/report-system/report-system.scm

@@ -687,7 +687,7 @@
 (export gnc:accounts-get-commodities)
 (export gnc:get-current-account-tree-depth)
 (export gnc:accounts-and-all-descendants)
-(export gnc:acccounts-get-all-subaccounts)
+(export gnc:acccounts-get-all-subaccounts) ;deprecated
 (export gnc:make-stats-collector)       ;deprecated
 (export gnc:make-drcr-collector)        ;deprecated
 (export gnc:make-value-collector)

gnucash/report/report-system/report-utilities.scm

@@ -146,14 +146,14 @@ construct gnc:make-gnc-monetary and use gnc:monetary->string instead.")
 
 ;; Get all children of this list of accounts.
 (define (gnc:acccounts-get-all-subaccounts accountlist)
+  (issue-deprecation-warning "gnc:acccounts-get-all-subaccounts is unused.")
   (append-map gnc-account-get-descendants-sorted
               accountlist))
 
 ;; Return accountslist *and* their descendant accounts
 (define (gnc:accounts-and-all-descendants accountslist)
   (sort-and-delete-duplicates
-   (append accountslist
-           (gnc:acccounts-get-all-subaccounts accountslist))
+   (apply append accountslist (map gnc-account-get-descendants accountslist))
    (lambda (a b)
      (string<? (gnc-account-get-full-name a) (gnc-account-get-full-name b)))
    equal?))