TF: fix CF buckets formatting
TF: fix CF buckets formatting

2 spaces is standard. Use it everywhere, including in buckets.tf, which
contains bucket definitions for CF.

alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf