if PR have no .py files, do not use 'python coverage run', to speedup unit test (#29739)

* reopen python coverage --include for test, test=develop

* if no .py file modified, not use coverage run, test=develop

* remove test code, test=develop

* add WITH_INCREMENTAL_COVERAGE, test=develop

* refine if else, test=develop

cmake/generic.cmake

@@ -843,7 +843,7 @@ function(py_test TARGET_NAME)
     set(multiValueArgs SRCS DEPS ARGS ENVS)
     cmake_parse_arguments(py_test "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
 
-    if(WITH_COVERAGE)
+    if(WITH_COVERAGE AND NOT (WITH_INCREMENTAL_COVERAGE AND "$ENV{PADDLE_GIT_DIFF_PY_FILE}" STREQUAL ""))
       add_test(NAME ${TARGET_NAME}
               COMMAND ${CMAKE_COMMAND} -E env FLAGS_init_allocated_mem=true FLAGS_cudnn_deterministic=true
               FLAGS_cpu_deterministic=true

python/paddle/fluid/tests/unittests/CMakeLists.txt

@@ -219,7 +219,7 @@ function(py_test_modules TARGET_NAME)
     set(multiValueArgs MODULES DEPS ENVS)
     cmake_parse_arguments(py_test_modules "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
 
-    if(WITH_COVERAGE)
+    if(WITH_COVERAGE AND NOT (WITH_INCREMENTAL_COVERAGE AND "$ENV{PADDLE_GIT_DIFF_PY_FILE}" STREQUAL ""))
         add_test(NAME ${TARGET_NAME}
                 COMMAND ${CMAKE_COMMAND} -E env PYTHONPATH=${PADDLE_BINARY_DIR}/python ${py_test_modules_ENVS}
                 COVERAGE_FILE=${PADDLE_BINARY_DIR}/python-coverage.data