Yardstick real-time influxdb KPI reporting regressions

Yardstick real-time influxdb KPI reporting regressions

JIRA: YARDSTICK-989

We used to have real-time influxdb reporting of test KPIs. The user
could monitor using grafana and see the real-time output.
The record format was changed to now only report KPIs at the end of the
test.
This is a problem for test cases which run for a long duration,  we need
to wait until the end of the test execution to get any results from
influxdb. If the test fails in between or doesn't exit cleanly for some
reason, we are left with no results stored in influxdb which gives the
user no information.
This is also a regression from the previous behaviour.

Change-Id: I0f476dff9162a359f0286fb421f2e9c4befaa5cc
Signed-off-by: chenjiankun <chenjiankun1@huawei.com>