increase max fee rate to 150 sat/byte
increase max fee rate to 150 sat/byte

Summary: the time for a tx to be confirmed in 2 blocks is currently around 115 sat/byte, so we increase this upper threshold

Reviewers: benchan, ben

Reviewed By: ben

Subscribers: ben

Differential Revision: https://phabricator.bitgo.com/D4354

BitGo/BitGoJS,BitGo/BitGoJS,BitGo/BitGoJS,BitGo/BitGoJS