Refactor OpenFlow sw/link scalability and longevity tests

Refactor OpenFlow sw/link scalability and longevity tests

- Remove Scalability.robot resource
- Create WorkflowsOpenFlow.robot and WorkflowsL2switch.robot
- Modify longevity to use full mesh topology workflow
- Add flow 10K flow add/delete check to all tests.
- Add error messages in case of failure.
- Add topology discovery time and plot for it.
- Add JVM monitoring.
- Remove redundant sw scale test.

This goes with https://git.opendaylight.org/gerrit/#/c/47254

Change-Id: I7773ff1b2e7c6b36de46a51db8aa38994c282f30
Signed-off-by: Luis Gomez <ecelgp@gmail.com>