Rename steel@chromium.org to rkc in OWNERS files

Same person, just the account name changed.

BUG=none
TEST=none

Review-Url: https://codereview.chromium.org/2780183003
Cr-Original-Commit-Position: refs/heads/master@{#460602}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 0b5f234c63a2e2c628d400290b343da70df12d2b
1 file changed