un-skip test of launching network of 13 platforms and 8 instruments

 (locally this test ran in 329.336s)
add test_instrument_reset_externally
add test_adverse_activation_sequence
indicate expected_state=ResourceAgentState.STREAMING in _instruments_start_streaming
some refactor to facilitate further test cases
add test_with_instrument_directly_put_into_streaming
add test_with_instrument_directly_stopped
minor cleanup: remove duplicate import; reformat a log msg
cleanup: remove unreachable conditioned code and align some logging to common pattern in platform agent
remove obsolete TODO comment
fix typo in condition under logging.TRACE
adjust a few log statements for consistency (use platform_id as prefix as general pattern)
adjust log statements for consistency (use platform_id as prefix as general pattern)
fix missing argument in call to _remove_exclusive_access in rollback section
explicitly verify expected mission events including validation of execution_status field value
Merge pull request #2199 from carueda/platform_agent_robustness

additional platform agent tests to check robustness