ZTS: Remove TXG_TIMEOUT from dedup_quota test (openzfs#17150)

It seems `fio` in `ddt_dedup_vdev_limit` overwhelms the system
with the amount of dirty data caused by DDT updates within one
TXG due to tiny 1KB records used, while I see no reason for this
test to extend the TXGs beyond default.

Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Reviewed-by: Allan Jude <[email protected]>
Reviewed-by: @ImAwsumm
Reviewed-by: Tony Hutter <[email protected]>

Author: amotin

tests/zfs-tests/tests/functional/dedup/dedup_quota.ksh

@@ -50,8 +50,6 @@ VDEV_GENERAL="$TEST_BASE_DIR/vdevfile.general.$$"
 VDEV_DEDUP="$TEST_BASE_DIR/vdevfile.dedup.$$"
 POOL="dedup_pool"
 
-save_tunable TXG_TIMEOUT
-
 # we set the dedup log txg interval to 1, to get a log flush every txg,
 # effectively disabling the log. without this it's hard to predict when and
 # where things appear on-disk
@@ -66,7 +64,6 @@ function cleanup
 		destroy_pool $POOL
 	fi
 	log_must rm -fd $VDEV_GENERAL $VDEV_DEDUP $MOUNTDIR
-	log_must restore_tunable TXG_TIMEOUT
 	log_must restore_tunable DEDUP_LOG_TXG_MAX
 	log_must restore_tunable DEDUP_LOG_FLUSH_ENTRIES_MIN
 }
@@ -84,7 +81,6 @@ function do_setup
 	# Use 'xattr=sa' to prevent selinux xattrs influencing our accounting
 	log_must zpool create -o ashift=12 -f -O xattr=sa -m $MOUNTDIR $POOL $VDEV_GENERAL
 	log_must zfs set compression=off dedup=on $POOL
-	log_must set_tunable32 TXG_TIMEOUT 600
 }
 
 function dedup_table_size