[Build] Strip armv7 artifacts (#35832)

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Closes #35832

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/35832 from gnossen:strip_armv7 0cb7a3122c
PiperOrigin-RevId: 605401618

tools/run_tests/artifacts/artifact_targets.py

@@ -152,6 +152,7 @@ class PythonArtifact:
             environ["PIP"] = "/opt/python/{}/bin/pip3".format(self.py_version)
             environ["GRPC_SKIP_PIP_CYTHON_UPGRADE"] = "TRUE"
             environ["GRPC_SKIP_TWINE_CHECK"] = "TRUE"
+            environ["LDFLAGS"] = "-s"
             return create_docker_jobspec(
                 self.name,
                 "tools/dockerfile/grpc_artifact_python_linux_{}".format(