[ios] Fix font for ClearBrowsingDataTableView Button

UIButton's don't handle dynamic types well. So we'll keep it fixed at a bold 17px.

Screenshots: https://drive.google.com/file/d/1befS0btYrluxxdfjZ-RJJ4aUnluyylX8/view?usp=sharing
https://drive.google.com/file/d/1tQSYQrDqmWuWhNVmJkYxjHy9Yp75OZ9L/view?usp=sharing

Bug: 865008

Change-Id: Ic76e8264123b647cfe19e580e1abdd98b9e6a229
Reviewed-on: https://chromium-review.googlesource.com/1145227
Commit-Queue: Chris Lu <thegreenfrog@chromium.org>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576929}
1 file changed