Remove a duplicated job

This was first added in b481b67, but 197e91f added
-DUNIVERSAL_PARSER to the Compilers workflow as well.

Given the nature of this test and the fact that it also runs make
test-all besides make test, I think it's better to keep only the
Compilers one.

.github/workflows/ubuntu.yml

@@ -41,8 +41,6 @@ jobs:
           - test_task: check
             configure: '--enable-shared --enable-load-relative'
           - test_task: test-all TESTS=--repeat-count=2
-          - test_task: test-all
-            configure: 'cppflags=-DUNIVERSAL_PARSER'
           - test_task: test-bundler-parallel
           - test_task: test-bundled-gems
       fail-fast: false