[Relax] Skip 1-D inputs in CombineParallelMatmul

[Nanmur]

Motivation

CombineParallelMatmul assumes both operands have matrix dimensions when it concatenates RHS tensors and splits the combined output. Valid matmul expressions with a 1-D operand therefore crash the pass:

• A vector LHS produces a 1-D output, but the rewrite constructs relax.split(axis=1).
• A vector RHS makes the batch-dimension loop use rhs_dim - 2, which underflows and leads to an out-of-bounds shape access.

Changes

• Skip rewrite groups whose RHS rank is less than two.
• Skip rewrite groups whose shared LHS rank is less than two.
• Add regression tests for both vector-LHS and vector-RHS matmul branches, verifying that the pass leaves valid unsupported patterns unchanged.

Testing

• python -m pytest tests/python/relax/test_transform_combine_parallel_matmul.py -q (14 passed)
• Release/LLVM source build on Windows
• Ruff check and format check
• clang-format dry run
• ASF header and file-type checks

Fixes #20197