Remove redundant flags, add debug flags and no-var-tracking

[iamashwin99]

This MR :

• Fixes #65 Henning has found in his experiments that the octopus configure script dosent use the FFLAGS at all which we are setting, we can hence remove it from here to reduce clutter. For eg the sample output from octopus dosent include a section on FFLAGS:

  Version                : 12.1
  Commit                 :
  Build time             : Mon Feb 27 21:57:54 CET 2023
  Configuration options  : maxdim3 openmp mpi sse2 avx libxc5 libxc_fxc
  Optional libraries     : cgal metis netcdf parmetis pfft nlopt
  Architecture           : x86_64
  C compiler             : /opt_mpsd/linux-debian11/dev-23a/sandybridge/spack/opt/spack/linux-debian11-sandybridge/gcc-11.3.0/openmpi-4.1.4-4lehnqllo3r6t45ix2wrdcew6lfwsdgw/bin/mpicc (/opt_mpsd/linux-debian11/dev-23a/sandybridge/spack/lib/spack/env/gcc/gcc)
  C compiler flags       : -g -O2
  C++ compiler           : /opt_mpsd/linux-debian11/dev-23a/sandybridge/spack/lib/spack/env/gcc/g++
  C++ compiler flags     : -g -O2
  Fortran compiler       : /opt_mpsd/linux-debian11/dev-23a/sandybridge/spack/opt/spack/linux-debian11-sandybridge/gcc-11.3.0/openmpi-4.1.4-4lehnqllo3r6t45ix2wrdcew6lfwsdgw/bin/mpif90 (/opt_mpsd/linux-debian11/dev-23a/sandybridge/spack/lib/spack/env/gcc/gfor
  Fortran compiler flags : -O2 -ffree-line-length-none -fallow-argument-mismatch -fallow-invalid-boz -fopenmp

• Fixes https://github.com/fangohr/octopus-in-spack/issues/61 We pass the no vartracking assignments flag to speed up compilation when debugging is required. gcc 10+ fortran does something called Variable Tracking at Assignments This is enabled by default and to disable it we add -fno-var-tracking-assignments.

• Fixes #64 In the octopus in spack package, we do not set the C flags and CXX flags that we set when using our internal configure wrapper. Such as -O2

• Fixes #69 The debug flags -g were being used even when on ~debug variant.