LU-13449 tests: fix recovery-small test_140b check

The recovery timer is printed in MM:SS format, but the current test
is unhappy if the SS part is printed as "08" or "09" since that is
interpreted by bash as an invalid octal number.  Also, the current
check does not handle the case if recovery is longer than a minute.

Change the code to convert MM:SS back to seconds for the comparison.

Test-Parameters: trivial testlist=recovery-small env=ONLY=140
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Ie1dc77a88bb0e8fd5025f2b5ca57d4a61d3ebbe5
Reviewed-on: https://review.whamcloud.com/39909
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>