[mlir][linalg] Simplify `createWriteOrMaskedWrite` (NFC) (#141567)
This patch removes `inputVecSizesForLeadingDims` from the parameter list
of `createWriteOrMaskedWrite`. That argument is unnecessary - vector
sizes can be obtained from the `vecToStore` parameter. Since this doesn't
change behavior or test results, it's marked as NFC.
Additional cleanups:
* Renamed `vectorToStore` to `vecToStore` for consistency and brevity.
* Rewrote a conditional at the end of the function to use early exit,
improving readability:
```cpp
// BEFORE:
if (maskingRequried) {
Value maskForWrite = ...;
write = maskOperation(write, maskForWrite);
}
return write;
// AFTER
if (!maskingRequried)
return write;
Value maskFroWrite = ...;
return vector::maskOperation(builder, write, maskForWrite);
```