Remove character encodings; fix spec

@sgrgic @sasagajic i have no idea why this spec started failing.
silverpop advised that they don't allow { and } characters...  but currently we do that filtering on the other side
https://github.com/lumoslabs/lumos_data_warehouse/commit/80e46dc7864f049486624fa1f8e4e48e1669ae34

[Refs #58848868]