[Build] Fix use_openssl=true (grpc#39380)

Fixed the bug in Bazel Tests passing the parameter incorrectly when
enabling `third_party:use_openssl`. (Introduced from
grpc#39188)

Author: veblush

.bcr/presubmit.yml

@@ -38,7 +38,7 @@ tasks:
     build_flags:
     - '--cxxopt=-std=c++17'
     - '--host_cxxopt=-std=c++17'
-    - '--//third_party:use_openssl=true'
+    - '--define=@grpc//third_party:use_openssl=true'
     build_targets:
       - "@grpc//:grpc"
       - "@grpc//:grpc_unsecure"

tools/bazelify_tests/test/bazel_build_with_bzlmod_linux.sh

@@ -53,7 +53,7 @@ tools/bazel \
     --enable_bzlmod=true \
     --enable_workspace=false \
     --ignore_dev_dependency \
-    --//third_party:grpc_use_openssl=true \
+    --define=//third_party:grpc_use_openssl=true \
     -- \
     :all \
     -:grpcpp_csm_observability  # Needs google_cloud_cpp to be added to BCR