Revert "Mongo installation only needs to occur for Buildkite."
Revert "Mongo installation only needs to occur for Buildkite."

This reverts commit 46c2fa784bfcba8eba82f28607d1f6c91d30cff9.
Tests scripts are identical between Travis and Buildkite. Reverting for now.

EOSIO/eos,EOSIO/eos,EOSIO/eos,EOSIO/eos,EOSIO/eos