[OOBE] Remove the workaround to prevent Gaia screen show

when the app launch splash screen is shown. Pretty sure the workaround
is not required anymore.

Bug: b/113786350
Change-Id: I12c7c1ffec68ee9ab82ddd2b9966e213a3b2d170
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3627535


Auto-Submit: Roman Sorokin <rsorokin@chromium.org>
Reviewed-by: Polina Bondarenko <pbond@chromium.org>
Commit-Queue: Polina Bondarenko <pbond@chromium.org>
Cr-Commit-Position: refs/heads/main@{#999812}