Do not copy local insets to IME during insets traversal

WindowState traversal will be including the IME window because of the
idea that the IME was attached to a window, and something applied to a
window state should also applied to the insets.

However, this is no longer true, also the IME doesn't rely on the target
window to calculate the insets correctly. Skip copy of local insets
sources to IME window to avoid accidental inheritance of insets from the
IME target window.

Bug: 421000153
Bug: 441434842
Test: InsetsPolicyTests
Test: Check the bug report and verify with bubble test apps
Flag: com.android.window.flags.relative_insets
Change-Id: I2a7f02573c9c313fa970594814e591666f89029e