Cleanup value_set_dereferencet's internal API [blocks: #2310]

[tautschnig]

Several parameters were no longer used and thus unnecessarily being passed
around.

• Each commit message has a non-empty body, explaining why the change was made.
• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
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[allredj]

✔️
Passed Diffblue compatibility checks (cbmc commit: 71d6013).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/90952270