Quick fixes for two ZTS failures

On FreeBSD 14, these two tests started erroring out like the
objects they're attempting to examine don't exist.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes #12165

tests/zfs-tests/tests/functional/cli_root/zdb/zdb_checksum.ksh

@@ -50,6 +50,7 @@ listing=$(ls -i $init_data)
 set -A array $listing
 obj=${array[0]}
 log_note "file $init_data has object number $obj"
+sync_pool $TESTPOOL
 
 output=$(zdb -ddddddbbbbbb $TESTPOOL/$TESTFS $obj 2> /dev/null \
     |grep -m 1 "L0 DVA" |head -n1)

tests/zfs-tests/tests/functional/cli_root/zdb/zdb_objset_id.ksh

@@ -57,6 +57,7 @@ listing=$(ls -i $init_data)
 set -A array $listing
 obj=${array[0]}
 log_note "file $init_data has object number $obj"
+sync_pool $TESTPOOL
 
 output=$(zdb -d $TESTPOOL/$TESTFS)
 objset_id=$(echo $output | awk '{split($0,array,",")} END{print array[2]}' |