LU-12229 tests: fix "bad substitution" error

LU-12229 tests: fix "bad substitution" error

In newer bash version, the special characters is invalid in the
usage of indirect variable expansion {!word}. For example,
	# a=lustre,pool
	# echo ${!a}
	-bash: lustre,pool: bad substitution
To avoid "bad sustitution" error, pool_new command is used in
test_1j and test_1k directly.

Test-Parameters:trivial clientdistro=el8 testlist=ost-pools
Signed-off-by: Emoly Liu <emoly@whamcloud.com>
Change-Id: Ifce4616cd7f314416fe5fa09f8fba846ae45bcef
Reviewed-on: https://review.whamcloud.com/36243
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Li Xi <lixi@ddn.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>