[CI] address cmakelint warnings about whitespace (#9674)

src/CMakeLists.txt

@@ -11,7 +11,7 @@ set_source_files_properties(
   PROPERTIES SKIP_UNITY_BUILD_INCLUSION ON)
 target_sources(objxgboost PRIVATE ${RABIT_SOURCES})
 
-if (USE_CUDA)
+if(USE_CUDA)
   file(GLOB_RECURSE CUDA_SOURCES *.cu *.cuh)
   target_sources(objxgboost PRIVATE ${CUDA_SOURCES})
 endif()
@@ -22,7 +22,7 @@ target_include_directories(objxgboost
   ${xgboost_SOURCE_DIR}/dmlc-core/include
   ${xgboost_SOURCE_DIR}/rabit/include)
 
-if (LOG_CAPI_INVOCATION)
+if(LOG_CAPI_INVOCATION)
   target_compile_definitions(objxgboost PRIVATE -DLOG_CAPI_INVOCATION=1)
 endif()