Revert "Added max parallelism to data blocks to enable faster processing"

This reverts commit f01aa374fddd890355539fa8bfa4659af40a370f.

Revert async - memory consumption out of control
Revert "tersified"

This reverts commit 3c8e1f20b07e2d178ae3e3fe488b12d3effcf359.

Revert async - memory consumption out of control
Revert "Handle cases with missing _id, and bypass merge for single drop buckets"

This reverts commit 18a2f9049b55555671b7a1fd8ab8a507829b37a9.

Revert async - memory consumption out of control
Revert "Intial TPL dataflow implementation for async operation"

This reverts commit 0822079c8e8d0755a5234d4f3d71970858051878.

Revert async - memory consumption out of control
Reverting async bulk push