Remove continue-on-error for test-bundled-gems

* Otherwise, it takes a very long time to notice those tests broke.

.github/workflows/macos.yml

@@ -46,13 +46,11 @@ jobs:
         env:
           MSPECOPT: "-ff" # not using `-j` because sometimes `mspec -j` silently dies
         if: matrix.test_task != 'test-bundled-gems' && !contains(github.event.head_commit.message, '[ci skip]')
-      # test-bundled-gems is separated for marking `continue-on-error` because it randomly fails.
       - name: Tests (test-bundled-gems)
         # Remove TEST_BUNDLED_GEMS_ALLOW_FAILURES=minitest if https://github.com/seattlerb/minitest/pull/798 resolved
         run: make -s ${{ matrix.test_task }} TEST_BUNDLED_GEMS_ALLOW_FAILURES=minitest
         env:
           RUBY_TESTOPTS: "-q --tty=no"
-        continue-on-error: true
         if: matrix.test_task == 'test-bundled-gems' && !contains(github.event.head_commit.message, '[ci skip]')
       - name: Leaked Globals
         run: make -s leaked-globals

.github/workflows/ubuntu.yml

@@ -74,13 +74,11 @@ jobs:
         env:
           MSPECOPT: "-ff" # not using `-j` because sometimes `mspec -j` silently dies
         if: matrix.test_task != 'test-bundled-gems' && !contains(github.event.head_commit.message, '[ci skip]')
-      # test-bundled-gems is separated for marking `continue-on-error` because it randomly fails.
       - name: Tests (test-bundled-gems)
         # Remove TEST_BUNDLED_GEMS_ALLOW_FAILURES=minitest if https://github.com/seattlerb/minitest/pull/798 resolved
         run: make -s ${{ matrix.test_task }} TEST_BUNDLED_GEMS_ALLOW_FAILURES=minitest
         env:
           RUBY_TESTOPTS: "-q --tty=no"
-        continue-on-error: true
         if: matrix.test_task == 'test-bundled-gems' && !contains(github.event.head_commit.message, '[ci skip]')
       - name: Leaked Globals
         run: make -s leaked-globals