Enable ABSL_FLAGS flag registration for onnxruntime_perf_test for mobile build (microsoft#25849)

### Description
`ABSL_FLAGS_STRIP_NAMES `is set to 1 by default to disable flag
registration when building for Android, iPhone, and "embedded devices".
So, running onnxruntime_perf_test on Android will see that flags are not
registered.

<img width="872" height="182" alt="image (2)"
src="https://github.com/user-attachments/assets/eb6a6772-cdff-4d60-a3c7-4352477e956c"
/>

Set `ABSL_FLAGS_STRIP_NAMES ` to 0 by default for all builds.

Author: chilo-ms

cmake/onnxruntime_unittests.cmake

@@ -1232,6 +1232,12 @@ if (NOT onnxruntime_ENABLE_TRAINING_TORCH_INTEROP)
       ${onnxruntime_perf_test_src_patterns}
       )
     onnxruntime_add_executable(onnxruntime_perf_test ${onnxruntime_perf_test_src} ${ONNXRUNTIME_ROOT}/core/platform/path_lib.cc)
+
+    # ABSL_FLAGS_STRIP_NAMES is set to 1 by default to disable flag registration when building for Android, iPhone, and "embedded devices".
+    # See the issue: https://github.com/abseil/abseil-cpp/issues/1875
+    # We set it to 0 for all builds to be able to use ABSL flags for onnxruntime_perf_test.
+    target_compile_definitions(onnxruntime_perf_test PRIVATE ABSL_FLAGS_STRIP_NAMES=0)
+
     if(MSVC)
       target_compile_options(onnxruntime_perf_test PRIVATE "$<$<COMPILE_LANGUAGE:CUDA>:SHELL:--compiler-options /utf-8>"
             "$<$<NOT:$<COMPILE_LANGUAGE:CUDA>>:/utf-8>")