[Enrollment] Disable cancel button for forced enrollments.

Before this change a cancellation button (presented as "Use as
a personal device" button) was shown on error screen when forced
enrollment (e.g. MODE_LOCAL_FORCED) failed.

Now the button is hidden on error screen for forced enrollment modes.
This should make user experience less confusing and make it clear that
forced enrollment is inescapable.

The visibility of the button is only confusing but does not actually
help to escape the forced enrollment: clicking the button results in
enrollment screen being shown again.

  "*EnrollmentErrorScreenTest.ErrorScreenData*"

Bug: b:238175743
Test: manual on a device.
Test: browser_tests --gtest_filter=\
Change-Id: Ifed9ee64d3d46e059417ce7cbbea3186c20f07cd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3758069
Reviewed-by: Roman Sorokin <rsorokin@chromium.org>
Commit-Queue: Artem Sumaneev <asumaneev@google.com>
Reviewed-by: Miriam Polzer <mpolzer@google.com>
Reviewed-by: Roman Aleksandrov <raleksandrov@google.com>
Cr-Commit-Position: refs/heads/main@{#1025766}