[ecash-herald] patch docker
Summary:
fix capitalization mismatch
in fixing the lint error thrown on WasmBuilder, did not update all instances of it
for some reason ... builds do not fail in this case. tho the app won't work.
Test Plan: docker build -f ecash-herald.Dockerfile -t ecash-herald_local .
Reviewers: #bitcoin_abc, PiRK
Reviewed By: #bitcoin_abc, PiRK
Differential Revision: https://reviews.bitcoinabc.org/D17358