EX-7553 - reduce b_es6_0 failover-part-3 duration

EX-7553 - reduce b_es6_0 failover-part-3  duration

Reduced recovery-mds-scale duration to 12 hours

Test-Parameters: trivial
Test-Parameters: austeroptions="-R" clientcount=4 clientdistro=el7.9 \
                 env=SLOW=yes failover=true iscsi=1 mdscount=2 \
                 mdssizegb=10 osscount=2 ostsizegb=2 serverdistro=el7.9 \
                 testgroup=failover-part-3

Change-Id: I791044863b5c52f44a0db36e816581b9d4655287
Signed-off-by: Charlie Olmstead <charlie@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/51099
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>