Fix failing mpich build tests (#19259)

By default Spack uses the latest (highest version) GCC 
compiler available, which might change across updates
of the Github CI environment.

Since a C compiler is always installed and `mpich~fortran`
will result in faster build times, avoid building the FORTRAN
interface as part of the test.

.github/workflows/linux_build_tests.yaml

@@ -29,7 +29,7 @@ jobs:
       matrix:
         package:
         - lz4  # MakefilePackage
-        - mpich  # AutotoolsPackage
+        - mpich~fortran  # AutotoolsPackage
         - tut  # WafPackage
         - py-setuptools  # PythonPackage
         - openjpeg  # CMakePackage