Fix standalone gflags search (#28930)

### Details:
- Unknown issue with `PACKAGE_PREFIX_DIR` after upgrading to cmake 3.30.
The PR replaces it with the explicit OV root directory definition.

### Tickets:
 - *ticket-id*

Author: Maxim-Doronin

src/plugins/intel_npu/tools/compile_tool/cmake/standalone.cmake

@@ -21,8 +21,9 @@ find_package(OpenVINO REQUIRED COMPONENTS Runtime)
 # gflags is distributed in sources in OpenVINO packages so we need to build it explicitly
 #
 
-if(EXISTS "${PACKAGE_PREFIX_DIR}/samples/cpp/thirdparty/gflags")
-    add_subdirectory("${PACKAGE_PREFIX_DIR}/samples/cpp/thirdparty/gflags" gflags EXCLUDE_FROM_ALL)
+get_filename_component(OpenVINO_PACKAGE_DIR "${OpenVINO_DIR}/../.." REALPATH)
+if(EXISTS "${OpenVINO_PACKAGE_DIR}/samples/cpp/thirdparty/gflags")
+    add_subdirectory("${OpenVINO_PACKAGE_DIR}/samples/cpp/thirdparty/gflags" gflags EXCLUDE_FROM_ALL)
 else()
     find_package(gflags REQUIRED)
 endif()

src/plugins/intel_npu/tools/protopipe/cmake/standalone.cmake

@@ -29,7 +29,8 @@ if (NOT yaml-cpp_FOUND)
 endif()
 
 if (NOT gflags_FOUND)
-    set(GFLAGS_SOURCES_PATH "${PACKAGE_PREFIX_DIR}/samples/cpp/thirdparty/gflags")
+    get_filename_component(OpenVINO_PACKAGE_DIR "${OpenVINO_DIR}/../.." REALPATH)
+    set(GFLAGS_SOURCES_PATH "${OpenVINO_PACKAGE_DIR}/samples/cpp/thirdparty/gflags")
     message(STATUS "gflags package was not found. Trying to find source package in ${GFLAGS_SOURCES_PATH}.")
     if(EXISTS ${GFLAGS_SOURCES_PATH})
         message(STATUS "gflags source package found. gflags will be built from sources.")

src/plugins/intel_npu/tools/single-image-test/cmake/standalone.cmake

@@ -27,8 +27,9 @@ add_subdirectory("${CMAKE_CURRENT_SOURCE_DIR}/../common" common EXCLUDE_FROM_ALL
 # gflags is distributed in sources in OpenVINO packages so we need to build it explicitly
 #
 
-if(EXISTS "${PACKAGE_PREFIX_DIR}/samples/cpp/thirdparty/gflags")
-    add_subdirectory("${PACKAGE_PREFIX_DIR}/samples/cpp/thirdparty/gflags" gflags EXCLUDE_FROM_ALL)
+get_filename_component(OpenVINO_PACKAGE_DIR "${OpenVINO_DIR}/../.." REALPATH)
+if(EXISTS "${OpenVINO_PACKAGE_DIR}/samples/cpp/thirdparty/gflags")
+    add_subdirectory("${OpenVINO_PACKAGE_DIR}/samples/cpp/thirdparty/gflags" gflags EXCLUDE_FROM_ALL)
 else()
     find_package(gflags REQUIRED)
 endif()