feat: separate bazel5 test for bazel ci

Signed-off-by: Sam Gammon <sam@elide.ventures>

.bazelci/presubmit.yml

@@ -1,7 +1,7 @@
 ---
 matrix:
-  bazel_version: ["5.4.0", "6.3.2", "7.0.0-pre.20230724.1"]
-  unix_platform: ["centos7", "debian10", "macos", "ubuntu2004"]
+  bazel_version: ["6.3.2", "7.0.0-pre.20230724.1"]
+  platform: ["centos7", "debian10", "macos", "ubuntu2004"]
 
 validate_config: 1
 buildifier: latest
@@ -16,6 +16,14 @@ tasks:
     test_targets:
       - "..."
 
+  kythe_ubuntu2004:
+    index_targets:
+      - "..."
+    index_targets_query: 'kind("java_(binary|import|library|plugin|test|proto_library) rule", ...)'
+    index_flags:
+      - "--define=kythe_corpus=github.com/sgammon/rules_graalvm"
+    index_upload_policy: "IfBuildSuccess"
+
 bcr_test_module:
   module_path: "example/integration_tests/bzlmod"
   matrix:
@@ -26,3 +34,21 @@ bcr_test_module:
       platform: ${{ platform }}
       build_targets:
         - "//..."
+---
+bazel: 5.4.0
+
+matrix:
+  platform: ["centos7", "debian10", "macos", "ubuntu2004"]
+
+tasks:
+  build:
+    include_json_profile:
+      - build
+      - test
+    shell_commands:
+      - echo "5.4.0" > .bazelversion
+      - echo "import %workspace%/tools/bazel/bazel5.bazelrc" > version.bazelrc
+    build_targets:
+      - "..."
+    test_targets:
+      - "..."