HDDS-3094. Save each output of smoketest executed multiple times

[adoroszlai]

What changes were proposed in this pull request?

Add a numeric suffix to Robot test output file names to avoid overwriting previous runs.

https://issues.apache.org/jira/browse/HDDS-3094

How was this patch tested?

Ran test in ozone-topology env, which calls readdata test twice (with different set of running datanodes).

$ cd hadoop-ozone/dist/target/ozone*/compose/ozone-topology
$ ./test.sh
...
Output:  /tmp/smoketest/ozone-topology/result/robot-ozone-topology-ozone-topology-readdata-scm.xml
...
Output:  /tmp/smoketest/ozone-topology/result/robot-ozone-topology-ozone-topology-readdata-scm-1.xml
...

https://github.com/adoroszlai/hadoop-ozone/runs/783624066

[elek]

+1 Nice trick.

Merging to the master. Thanks the patch @adoroszlai

[adoroszlai]

Thanks @elek for reviewing and committing it.