qa: do not use any time related suffix for *_op_timeouts

qa: do not use any time related suffix for *_op_timeouts

When testing the upgration, for the old version the *_op_timeouts
options' type is TYPE_FLOAT, but when parsing them by strict_strtod
it will failed with error:

  strict_strtod: garbage at end of string. got: '15m'

This commit will remove the 'm' suffix by switch the time to 900,
thus the old version still could parse it successfully.

Introduced-by: d060c9a768c6974d3b68e4d408edf78bba9e0e85
https://tracker.ceph.com/issues/51705
Signed-off-by: Xiubo Li <xiubli@redhat.com>
(cherry picked from commit bff813671603c02fdd7e51e88c4d701c2b56983b)