update BCR presubmit to match flags in .bazelrc (#17)

.bcr/java/presubmit.yml

diff --git a/.bcr/java/presubmit.yml b/.bcr/java/presubmit.yml
index 56a08d8..ed127b0 100644
--- a/.bcr/java/presubmit.yml
+++ b/.bcr/java/presubmit.yml
@@ -1,12 +1,27 @@
 matrix:
-  platform: ["ubuntu2204", "macos", "macos_arm64", "windows"]
-  bazel: [7.x]
+  platform: ["ubuntu2204", "macos", "macos_arm64"]
+  bazel: [7.x, 8.x, rolling]
 tasks:
-  run_tests:
+  run_tests_unix:
     name: run tests
     platform: ${{ platform }}
     bazel: ${{ bazel }}
     test_flags:
     - '--java_language_version=21'
+    - '--java_runtime_version=21'
+    - '--cxxopt=-std=c++17'
+    - '--host_cxxopt=-std=c++17'
+    test_targets:
+    - '@bazel_worker_java//...'
+  run_tests_windows:
+    name: run tests (windows)
+    platform: windows
+    bazel: ${{ bazel }}
+    test_flags:
+    - '--java_language_version=21'
+    - '--java_runtime_version=21'
+    - '--cxxopt=/std:c++17'
+    - '--host_cxxopt=/std:c++17'
+    - '--define=protobuf_allow_msvc=true'
     test_targets:
     - '@bazel_worker_java//...'

.bcr/proto/presubmit.yml

diff --git a/.bcr/proto/presubmit.yml b/.bcr/proto/presubmit.yml
index 52c154b..2ee0e9c 100644
--- a/.bcr/proto/presubmit.yml
+++ b/.bcr/proto/presubmit.yml
@@ -1,6 +1,6 @@
 matrix:
   platform: ["ubuntu2204", "macos", "macos_arm64", "windows"]
-  bazel: [7.x]
+  bazel: [7.x, 8.x, rolling]
 tasks:
   run_tests:
     name: build targets