FindHDF5: Fix regression in finding hdf5hl_fortran

Refactoring in commit fdfb0c06 accidentally dropped the name hdf5hl_fortran from the list of library names and replaced it with hdf5_hl_fortran. IIUC the latter name is when HDF5 is built with CMake and the former name is for other build systems. Since this is the non-CMake code path, user the former name.

Closes: #16233 (closed)