GAPIC v2: need new surface for LRO client, and need v2 surfaces to use it

[noahdietz]

It was pointed out that we are still using the "old gapic surface" in our generated LRO client. This client is a dependency of all GAPICs with LRO functionality. They use it under the hood and we will need to change GAPIC internals for "new surface" clients to use that "new surface" LRO.

They also have an accessor to make this client available to end users. This means that if we change the LRO client surface initialized for v2 surface clients, we will create a breaking change. As such, we need to come up with a means of mitigating the breakage.

Tasks:

• generate "new surface" for LRO package
• release "new surface" for LRO package
• add "new surface" usage into "new surface" gapic generated code

[noahdietz]

cc: @ajupazhamayil @saranshdhingra

[noahdietz]

cl/621250900 to enable "new surface" generation (hopefully)

[noahdietz]

bazel rule update was merged and I confirmed that the generated asset contains the "new surface" client as well. Waiting for automation to produce it in a PR here.

[noahdietz]

googleapis/google-cloud-php#7196 contains the regen

[noahdietz]

Reassigning to Brent for now, he offered to get the LRO gapic v2 surface generated.