[XLA] Fix #17090 a problem in IrArray::Index::SourceIndexOfTranspose.

[XLA] Fix #17090 a problem in IrArray::Index::SourceIndexOfTranspose.

Agebraic simplification transforms bitcast-equivalent transpose/reshape
instructions to bitcast instructions before IR emission. As such, we should
skip the checking on whether a transpose/reshape instruction is
bitcast-equivalent or not during IR emission. Remove the call from
IrArray::Index::SourceIndexOfTranspose to ShapeUtil::TransposeIsBitcast. Also
remove the call from IrArray::Index::SourceIndexOfReshape to
ShapeUtil::ReshapeIsBitcast.

Remove the calls to ShapeUtil::TransposeIsBitcast and
ShapeUtil::ReshapeIsBitcast from NotWorthHoistingIndividually
because layout assignment hasn't been done there yet. Instead, returns true
when the input is a transpose or reshape instruction, to prevent it from
being hoisted out of loops.

Add a check to ShapeUtil::TransposeIsBitcast and ShapeUtil::ReshapeIsBitcast
to make sure that both input shape and output shape have layouts.

Add two test cases.

PiperOrigin-RevId: 187093399