[ci] prevent trailing whitespace, ensure files end with newline (#6373)

tests/cpp_tests/testutils.cpp

@@ -277,7 +277,7 @@ namespace LightGBM {
   /*!
    * Pushes data from 1 thread into a Dataset based on thread_id and nrows.
    * e.g. with 100 rows, thread 0 will push rows 0-49, and thread 2 will push rows 50-99.
-   * Note that rows are still pushed in microbatches within their range. 
+   * Note that rows are still pushed in microbatches within their range.
    */
   void TestUtils::PushSparseBatch(DatasetHandle dataset_handle,
                                   int32_t nrows,

windows/LightGBM.vcxproj.filters

@@ -351,4 +351,4 @@
       <Filter>src\utils</Filter>
     </ClCompile>
   </ItemGroup>
-</Project>
\ No newline at end of file
+</Project>