LU-15626 tests: Fix "error" reported by shellcheck for recovery-mds-scale

LU-15626 tests: Fix "error" reported by shellcheck for recovery-mds-scale

This patch fixes "error" issues reported by shellcheck
for file lustre/tests/recovery-mds-scale.sh. This patch
also moves spaces to tabs.

Lustre-change: https://review.whamcloud.com/46865
Lustre-commit: a98728e4fd673ebe7a7d1d3f15a5a06d1efec9e3

Test-Parameters: trivial clientcount=6 mdtcount=2 mdscount=2 osscount=2 austeroptions=-R failover=true iscsi=1 env=FAILOVER_PERIOD=180,DURATION=600,SLOW=no testlist=recovery-mds-scale
Signed-off-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Change-Id: I6c098809835950e1f781e04a6898895592407948
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50628
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>