Remove tariff-fetch monkey patches

[alxsmith]

What

#473 introduced monkey patches to get around tariff fetch bugs. Once the pacakage has addressed the underlying issue, remove the monkey patches and verify the upstream fix resolved the issue.

Why

Long-term these issues should be handled upstream, not covered up with patches. The file now carries six monkey-patches against a pinned private tariff_fetch: xdrlib stub, broken t import, direct-GET rider fetch, schema relaxation, calc-factor folding, empty-band safety, non-interactive property resolver, and the new dedup.

How (optional)

Deliverables

• Monkey patches removed
• re-run tariff fetch for MD utilities and verify no diff on resulting tariffs

[linear]

RDP-234