STYLE: Replace indentation tabs with spaces

Use of spaces for indentation in new commits is already prevented by the
pre-commit style check, but this is not enforced for existing repo
contents.

Change-Id: I4020be06de7b1edffb494a309b802df5f2d2974b
Merge topic 'Indentation-Tabs'

64e2a52 STYLE: Replace indentation tabs with spaces