Revert "core: Update certificates as late as possible"

This reverts commit 202a9bcd because it caused
some test failures.
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Status Job ID Name Coverage
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failed SlapOS-Master.UnitTest-Master

01:10:45

passed SlapOS.Eggs.UnitTest-Jerome.Python2

passed SlapOS.Eggs.UnitTest-Jerome.Python3

passed SlapOS.Eggs.UnitTest-Master.Python2

passed SlapOS.Eggs.UnitTest-Master.Python3

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passed SlapOS.Eggs.UnitTest-Master.Python2

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passed SlapOS.Eggs.UnitTest-Master.Python2

passed SlapOS.Eggs.UnitTest-Master.Python2