Avoid re-launch button show after split switching

Due to difference of both side insets value, split bounds will
change after split switching. But bounds difference are actually
small. For users, they might not notice bounds change but re-launch
button show there might cause them confused.

Igonre insets difference and make them same as the larger one on split
axis. This will offset drag target position but should cause bad UX
experience because the offset should be very small and both insest
should not have big difference on general case.

Fix: 236400046
Test: manual
Test: pass existing tests
Change-Id: I91d3a43015b7ef0a35c4e755de085053dfb9977b