[mlir][vector] Fix dominance error in warp vector distribution (#77771)

This commit fixes a test in `vector-warp-distribute.mlir` when
`MLIR_ENABLE_EXPENSIVE_PATTERN_API_CHECKS` is enabled.

```
within split at /usr/local/google/home/springerm/mlir_public/llvm-project/mlir/test/Dialect/Vector/vector-warp-distribute.mlir:1 offset :18:10: error: operand #0 does not dominate this use
    %1 = vector.extract %0[9] : f32 from vector<64xf32>
         ^
within split at /usr/local/google/home/springerm/mlir_public/llvm-project/mlir/test/Dialect/Vector/vector-warp-distribute.mlir:1 offset :18:10: note: see current operation: %1 = "affine.apply"(%8) <{map = affine_map<()[s0] -> (s0 ceildiv 2)>}> : (index) -> index
within split at /usr/local/google/home/springerm/mlir_public/llvm-project/mlir/test/Dialect/Vector/vector-warp-distribute.mlir:1 offset :18:10: note: operand defined here (op in a child region)
"func.func"() <{function_type = (index) -> f32, sym_name = "vector_extract_1d"}> ({
^bb0(%arg0: index):
  %0:2 = "vector.warp_execute_on_lane_0"(%arg0) <{warp_size = 32 : i64}> ({
    %7 = "some_def"() : () -> vector<64xf32>
    %8 = "arith.constant"() <{value = 9 : index}> : () -> index
    %9 = "vector.extractelement"(%7, %8) : (vector<64xf32>, index) -> f32
    "vector.yield"(%9, %7) : (f32, vector<64xf32>) -> ()
  }) : (index) -> (f32, vector<2xf32>)
  %1 = "affine.apply"(%8) <{map = affine_map<()[s0] -> (s0 ceildiv 2)>}> : (index) -> index
  %2 = "affine.apply"(%8) <{map = affine_map<()[s0] -> (s0 mod 2)>}> : (index) -> index
  %3 = "vector.extractelement"(%0#1, %2) : (vector<2xf32>, index) -> f32
  %4 = "arith.index_cast"(%1) : (index) -> i32
  %5 = "arith.constant"() <{value = 32 : i32}> : () -> i32
  %6:2 = "gpu.shuffle"(%3, %4, %5) <{mode = #gpu<shuffle_mode idx>}> : (f32, i32, i32) -> (f32, i1)
  "func.return"(%6#0) : (f32) -> ()
}) : () -> ()
LLVM ERROR: IR failed to verify after pattern application
```

The position at which `vector.extractelement` extracts must also be
distributed. The fix in `WarpOpExtractElement` is similar to
`WarpOpInsertElement`.