This parameter should support all types of writing of the bool type like parameter autovacuum_enabled.
So I fixed in global_temporary_table_v24-pg13.patch.
Thank you Wenjing for the new patch with the fix and the "VACUUM FULL GTT" support.
I have verified the above issue now its resolved.
Please check the below findings on VACUUM FULL.
postgres=# create global temporary table gtt(c1 int) on commit preserve rows; CREATE TABLE postgres=# vacuum FULL ; WARNING: global temp table oldest FrozenXid is far in the past HINT: please truncate them or kill those sessions that use them. VACUUM
