WMAgent: Move the creation of the metadata table wma_init under WMCore

[todor-ivanov]

Impact of the new feature
WMAgent

Is your feature request related to a problem? Please describe.

While refactoring the process of WMAgent initialization, we introduced one new table with metadata called wma_init, which is to be filled in with data collected at init time. Currently the table is created by the run.sh, which is the default entrypoint for the docker container, but the proper place for the table to be defined is inside the WMCore code, where all other parts of the SQL schema are set - i.e. at: https://github.com/dmwm/WMCore/tree/master/src/python/WMCore/Agent/Database

Describe the solution you'd like

Move the the wma_init table definition and creation inside the WMCore code, while letting the initialization scripts only fill in the appropriate data.

Describe alternatives you've considered
leave it as it is.

Additional context
This issue is a followup on:

• Refactor/reorganize agent initialization and manage actions #11627

And is part of the following meta issue:

• Deploy and run WMAgent with Docker container #11314