[flang] Fix flang build after #83132 (#83253)

This fix is a temporary workaround. `LowerHLFIRIntrinsics.cpp` should be
using the greedy pattern rewriter or a manual IR traversal. All patterns
in this file are rewrite patterns. The test failure was caused by
`replaceAllUsesWith`, which is not supported by the dialect conversion;
additional asserts were added recently to prevent incorrect API usage.
These trigger now.

Alternatively, turning the patterns into conversion patterns and
specifying a type converter may work.

Failing test case:
`Fortran/gfortran/regression/gfortran-regression-compile-regression__inline_matmul_14_f90.test`