[epic] Adapt migration test coverage and its migration matrix for SLE 15 SP6
In this epic we will track all the necessary changes for the migration test matrix, changes in the spreadsheet itself and in the job group configuration.
- Follow new PRD for SLE 15 SP5
- Make our own improvements in the matrix, which means that we might decide in the squad to drop some test coverage or add a few more cases and the way we would organize and name all.
AC1: Adapt migration matrix test coverage according to PRD for SLE 15 SP6
AC2: Make additional adaptions based on analysis of current test coverage