.github: let "make leaked-globals" run in parallel

This target can be a build matrix.  Also it does not make sense to test
it on mjit.

Author: shyouhei

.github/workflows/macos.yml

@@ -5,7 +5,7 @@ jobs:
     runs-on: macos-latest
     strategy:
       matrix:
-        test_task: [ "check", "test-bundler", "test-bundled-gems" ]
+        test_task: [ "check", "test-bundler", "test-bundled-gems", "leaked-globals" ]
       fail-fast: false
     if: "!contains(github.event.head_commit.message, '[ci skip]')"
     steps:
@@ -52,8 +52,6 @@ jobs:
           # Remove minitest from TEST_BUNDLED_GEMS_ALLOW_FAILURES if https://github.com/seattlerb/minitest/pull/798 is resolved
           # rss needs to add workaround for the non rexml environment
           TEST_BUNDLED_GEMS_ALLOW_FAILURES: "minitest,xmlrpc,rss,rexml"
-      - run: make -s leaked-globals
-        working-directory: build
       - uses: k0kubun/action-slack@v2.0.0
         with:
           payload: |

.github/workflows/mjit.yml

@@ -54,8 +54,6 @@ jobs:
         working-directory: build
       - run: make $JOBS -s test-spec
         working-directory: build
-      - run: make -s leaked-globals
-        working-directory: build
       - uses: k0kubun/action-slack@v2.0.0
         with:
           payload: |

.github/workflows/ubuntu.yml

@@ -4,7 +4,7 @@ jobs:
   make:
     strategy:
       matrix:
-        test_task: [ "check", "test-bundler", "test-bundled-gems", "test-all TESTS=--repeat-count=2" ]
+        test_task: [ "check", "test-bundler", "test-bundled-gems", "test-all TESTS=--repeat-count=2", "leaked-globals" ]
         os: [ubuntu-latest, ubuntu-16.04]
         exclude:
           - test_task: test-bundler
@@ -64,8 +64,6 @@ jobs:
           # Remove minitest from TEST_BUNDLED_GEMS_ALLOW_FAILURES if https://github.com/seattlerb/minitest/pull/798 is resolved
           # rss needs to add workaround for the non rexml environment
           TEST_BUNDLED_GEMS_ALLOW_FAILURES: "minitest,xmlrpc,rss"
-      - run: make -s leaked-globals
-        working-directory: build
       - uses: k0kubun/action-slack@v2.0.0
         with:
           payload: |