Update datastore regression to use Entity/Key equality.

Source-Link: googleapis/synthtool@92006bb
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-python:latest@sha256:2e247c7bf5154df7f98cce087a20ca7605e236340c7d6d1a14447e5c06791bd6

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

The underlying GAPIC client uses protoplus for all requests and responses. However the underlying protos for ReadRowsResponse are never exposed to end users directly: the underlying chunks get merged into logic rows. The readability benefits provided by protoplus for ReadRows do not justify the costs. This change unwraps the protoplus messages and uses the raw protobuff message as input for row merging. This improves row merging performance by 10x. For 10k rows, each with 100 cells where each cell is 100 bytes and in groups of 100 rows per ReadRowsResponse, cProfile showed a 10x improvement:

old:          124266037 function calls in 68.208 seconds
new:          13042837 function calls in 7.787 seconds

There are still a few more low hanging fruits to optimize performance and those will come in follow up PRs

Certain code patterns in the generated surface are created by
iteration over data collections. This iteration order should be
deterministic in order to prevent spurious deltas in the generated surface.

Fixes #619

Fix #618. Removes aiohttp from required dependencies to lessen dependency tree for google-auth.

This will need to be looked at again as more folks use aiohttp and once the surfaces goes to public visibility.