* Add linear layer tests for model executor
* Refine linear layer tests for uncovered branches
* Refactor and enhance tests for linear layers
Refactor test_linear.py by removing unused imports and redundant code, and updating model configuration parameters. Add new tests for linear layers and their loading mechanisms.
* test: patch row-parallel alltoall in unit test
* test: avoid alltoall reshape failure in row-parallel
* test: expand linear coverage targets
* Refine linear tests per review feedback
* Fix linear tests for pre-sharded config and qkv fixture
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Co-authored-by: CSWYF3634076 <wangyafeng@baidu.com>
xunyoyo