WIP: use new matrix

Author: rnro

.github/workflows/matrices/plugin-tests.json

@@ -0,0 +1 @@
+{"config":[{"name":"Plugin tests (6.0)","swift_version":"6.0","runner":"ubuntu-latest","image":"swift:6.0-jammy","platform":"Linux","setup_command":"apt-get update -y -q && apt-get install -y -q curl","command":"curl -s https://raw.githubusercontent.com/rnro/grpc-swift-protobuf/package_plugins/dev/plugin-tests.sh | bash","command_arguments":""},{"name":"Plugin tests (nightly-6.0)","swift_version":"nightly-6.0","runner":"ubuntu-latest","image":"swiftlang/swift:nightly-6.0-jammy","platform":"Linux","setup_command":"apt-get update -y -q && apt-get install -y -q curl","command":"curl -s https://raw.githubusercontent.com/rnro/grpc-swift-protobuf/package_plugins/dev/plugin-tests.sh | bash","command_arguments":""},{"name":"Plugin tests (nightly-main)","swift_version":"nightly-main","runner":"ubuntu-latest","image":"swiftlang/swift:nightly-main-jammy","platform":"Linux","setup_command":"apt-get update -y -q && apt-get install -y -q curl","command":"curl -s https://raw.githubusercontent.com/rnro/grpc-swift-protobuf/package_plugins/dev/plugin-tests.sh | bash","command_arguments":""}]}

.github/workflows/pull_request.yml

@@ -28,12 +28,10 @@ jobs:
 
   plugin-tests:
     name: Plugin tests
-    uses: apple/swift-nio/.github/workflows/swift_matrix.yml@main
+    uses: apple/swift-nio/.github/workflows/swift_load_test_matrix.yml@main
     with:
       name: "Plugin tests"
-      matrix_linux_5_9_enabled: false
-      matrix_linux_5_10_enabled: false
-      matrix_linux_command: "./dev/plugin-tests.sh"
+      matrix_path: ".github/workflows/matrices/plugin-tests.json"
 
   cxx-interop:
     name: Cxx interop