OWNERS: tobiast -> ngeoffray.

This CL topic was created via:

  find . -name OWNERS | xargs grep -l tobiast | xargs sed \
  -i 's/tobiast/ngeoffray/g'

Plus appropriate repo start, git commit, repo upload commands:

  while read proj; do croot $proj ; repo start OWNERS-tobiast-ngeoffray ; \
  git commit -F ~/commit-message.txt; croot ; done \
  < ~/owners-projects.txt

  repo upload -t --br=OWNERS-tobiast-ngeoffray

No attempt was made to sort the files after the replacement.

Exempt-From-Owner-Approval: Both old and new owner are on this CL.
Test: Manually inspected the result.
Bug: 152399425
Change-Id: I2f100a71d399a7d4d46ea036fff564ff5c5dbda7