Revert reordering of tildeB fluxes and sources in ValenciaDivClean

[ncorsobh]

Proposed changes

An earlier PR (#5960) had reordered the source and flux terms in ValenciaDivClean in an attempt to make the system better-behaved. However, it was empirically found that this reduced the quality of the magnetic field evolution. Additionally, convergence tests for higher order FD do not work properly unless this change is undone.

Upgrade instructions

Code review checklist

• The code is documented and the documentation renders correctly. Run
  make doc to generate the documentation locally into BUILD_DIR/docs/html.
  Then open index.html.
• The code follows the stylistic and code quality guidelines listed in the
  code review guide.
• The PR lists upgrade instructions and is labeled bugfix or
  new feature if appropriate.

Further comments

@jyoo1042 This PR should merge into develop a change that you are already using. Please confirm that this is indeed the case. And if so, this will formally implement it, so you can disregard the local change that you are using.

[jyoo1042]

@ncorsobh yes. thank you!

[wthrowe]

Not a review of the code, but the "Upgrade instructions" are published in the documentation and release notes, so I don't think you actually want that content there.

[ncorsobh]

Not a review of the code, but the "Upgrade instructions" are published in the documentation and release notes, so I don't think you actually want that content there.

Didn't realize this, thanks! I just moved the comment to the "Further comments" section. Hopefully that's better!

[wthrowe]

Yep, that's fine.