refactor(providers)!: remove Galadriel provider

[gold-silver-copper]

Summary

• remove the Galadriel provider module and its public export
• delete the Galadriel ignored live tests
• update provider docs and changelog entries

Verification

• cargo fmt
• cargo check -p rig --all-targets --all-features
• cargo test -p rig --all-features --test core provider_layout