gnucash maint: Fix a missed g_value_dup_string and some no longer used variables.

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash/commit/7f0353ad (commit)
	from  https://github.com/Gnucash/gnucash/commit/8a7c5392 (commit)



commit 7f0353adc4b0dc73586bdf056dc5a97eda2599f9
Author: John Ralls <jralls at ceridwen.us>
Date:   Mon Feb 27 16:09:27 2023 -0800

    Fix a missed g_value_dup_string and some no longer used variables.



Summary of changes:
 libgnucash/engine/Transaction.c |  5 +----
 libgnucash/engine/kvp-frame.cpp | 15 ---------------
 2 files changed, 1 insertion(+), 19 deletions(-)