TrigValSteering: Skip test step if previous steps failed

Up to now, "exec" steps of Trigger ART tests (athena jobs) were executed independently. That is, if one step failed, the next one was executed regardless of the failure. However, in most or all multi-step test cases, the subsequent steps depend on inputs produced by the previous steps. This led to several bug reports being opened where the cause was mistakenly reported as "missing input" error from the second step of a test while there was a failure in the first step. Examples include ATR-20456 and ATR-20776 just to mention two.

With this MR, test exec steps will be skipped by default if previous steps finished with non-zero result code. This does not apply for "check" steps (log/histogram parsing) which are typically independent of each other. The setting can be changed individually with the newly added flag, if needed.