CI: Add test case for disabling Zifencei

Add a new test case to the CI pipeline when the Zifencei is disabled.
This ensures better coverage and prevents regressions for this specific
configuration.

Author: eleanorLYJ

.github/workflows/main.yml

@@ -87,6 +87,7 @@ jobs:
             make distclean && make ENABLE_Zbb=0 check -j$(nproc)
             make distclean && make ENABLE_Zbc=0 check -j$(nproc)
             make distclean && make ENABLE_Zbs=0 check -j$(nproc)
+            make distclean && make ENABLE_Zifencei=0 check -j$(nproc)
     - name: misalignment test in block emulation
       env:
         CC: ${{ steps.install_cc.outputs.cc }}