Do not reparent task or set windowing mode when layout task

#layoutTask is called while launching an activity, but the
TDA and the task windowing mode should already be resolved
earlier in RWC#getOrCreateRootTask. The result should not
be overridden again simply based on LaunchParams.

Bug: 219380819
Test: atest LaunchParamsControllerTests
Test: atest RootWindowContainerTests
Change-Id: I8c934a7b09d780f0d74513398decc3ac17f11b19