JS tests doing transaction operations must use majority writeConcern for drops

collation.js, misc_validation.js, do_txn_basic.js (per BF-9138) all need to be fixed to wait for both phases of two-phase drop to finish before starting transaction ops. Per SERVER-34372 and SERVER-33244, using majority write concern in an op will wait for the second phase of drop to finish before beginning the command, so that transaction ops don't run into lock conflict that cause the op (and entire transaction) to abort. Majority write concern should be added to the drop cmds.