Stub out end2end tests

Makefile

src/ruby/ext/grpc/rb_grpc_imports.generated.h

test/core/end2end/end2end_nosec_tests.c

test/core/end2end/end2end_tests.c

test/core/end2end/gen_build_yaml.py

test/core/end2end/tests/buffer_pool_client.c

test/core/end2end/tests/buffer_pool_server.c

tools/run_tests/sources_and_headers.json

tools/run_tests/tests.json

...end/tests/end2end_nosec_tests/end2end_nosec_tests.vcxproj

...s/end2end_nosec_tests/end2end_nosec_tests.vcxproj.filters

...oj/test/end2end/tests/end2end_tests/end2end_tests.vcxproj

...end2end/tests/end2end_tests/end2end_tests.vcxproj.filters