GHA: Enable Testing on macOS and Linux

Update GitHub actions to also execute the automated tests on macOS and
Linux platforms.

Relates to: #9427
Issue: rdar://165491718

Author: bkhouri

.github/workflows/pull_request.yml

@@ -27,9 +27,7 @@ jobs:
       linux_pre_build_command: ./.github/scripts/prebuild.sh
       linux_build_command: 'swift build --build-tests'
       enable_windows_checks: false
-      enable_macos_checks: true
-      macos_exclude_xcode_versions: "[{\"xcode_version\": \"16.4\"}]"
-      macos_build_command: 'swift build --build-tests'
+      enable_macos_checks: false
       enable_ios_checks: false
       enable_wasm_sdk_build: false
 
@@ -43,7 +41,7 @@ jobs:
     with:
       enable_cross_pr_testing: false
       # linux_publish_test_results: true
-      enable_linux_checks: false
+      enable_linux_checks: true
       # linux_os_versions: '["amazonlinux2", "bookworm", "noble", "jammy", "rhel-ubi9"]'
       linux_swift_versions: '["nightly-main", "6.2.0"]'
       linux_pre_build_command: ./.github/scripts/prebuild.sh
@@ -53,7 +51,7 @@ jobs:
       windows_swift_versions: '["nightly-main", "6.2.0"]'
       windows_pre_build_command: 'Invoke-Program .\.github\scripts\prebuild.ps1 -SkipAndroid'
       windows_build_command: 'Invoke-Program swift run --configuration release swift-test --scratch-path .test --parallel --experimental-xunit-message-failure --xunit-output windows-xunit.xml'
-      enable_macos_checks: false
+      enable_macos_checks: true
       # Need to run against macOS OSS Toolchain: https://github.com/swiftlang/github-workflows/issues/240
       macos_build_timeout: 480
       macos_xcode_versions: "[\"26.4\"]"
@@ -73,7 +71,7 @@ jobs:
     with:
       enable_cross_pr_testing: false
       # linux_publish_test_results: true
-      enable_linux_checks: false
+      enable_linux_checks: true
       linux_os_versions: '["amazonlinux2"]'
       linux_swift_versions: '["6.2.0"]'
       linux_pre_build_command: ./.github/scripts/prebuild.sh