Benchmarks/Michelson: bench unparsing without location stripping

Context

This MR adapts the benchmarks of the Michelson unparsing function unparse_data and unparse_code so that they don't measure the time spent to strip locations (which was recently added to these functions in !6403 (merged)). This is needed so that the benchmark can still be used to define the traversal gas constants for these functions without manually subtracting the cost of location stripping (see also #3687).

Manually testing the MR

Check that the unparsing benchmarks yield similar results on Alpha and K.

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR