[IEC][SEBA] Change SEBA deployment method to replicate upstream Opencord SIAB

Currently we deploy SEBA on top of IEC by using the simpler approach, with three set of charts: cord-platform -> seba -> att-workflow.
Although this method is mentioned in the Opencord Guide and it should work fine, in practice it seems to fail due to unpredictable race conditions, on both x86 and aarch64 setups (verified mostly on virtual PODs but could affect baremetal as well).

Looking at the upstream Opencord SEBA-in-a-Box Jenkins jobs, we see that the deployment of SEBA is done at a more granular level, component by component. This is described in the Opencord Guide:
https://guide.opencord.org/cord-6.1/profiles/seba/install.html#alternatively-install-seba-as-separate-components

For this purpose we will need to make use of the opencord automation-tools repo which can deploy SEBA-in-a-Box by running "make siab"

https://github.com/opencord/automation-tools/blob/master/seba-in-a-box/Makefile

Similar work has been done for integrating PONSim support in IEC ci-management:

https://gerrit.akraino.org/r/#/c/ci-management/+/1243/