In order to enforce that the test data provided for placeholders is of
the appropriate type (text vs binary), existing mismatches must be
resolved. This will prevent type mismatch issues from occurring when
switching builders to use python3.

Bug: 1273548
Change-Id: I83da25432b67853992d7771aba558fd38520a24e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3300310Reviewed-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Garrett Beaty <gbeaty@google.com>