The _startIndexBuildForRecovery() function does not set the index build protocol appropriately here.

Consequences can arise because of this issue, namely with rollback as we've seen in a build failure.

• Start an index build via _startIndexBuildForRecovery (originally a two-phase index build, but the protocol is set to kSinglePhase as that's the default value).
• Abort the index build due to rollback.
• Rollback will rebuild any required indexes, in this case, it builds our index above using the single-phase protocol, which is incorrect.