Remove --bootstrap-version command line option

[phlax]

description

once v2 has been fully removed the bootstrap-version no longer makes any sense (see https://www.envoyproxy.io/docs/envoy/latest/operations/cli#cmdoption-bootstrap-version)

apart from removing the cli option and related docs i think we also need to ensure that the logic for loading as v2 and upgrading is also removed

there is (also) some stuff in api/envoy/config/core/v3/config_source.proto that may need to change

[phlax]

cc @htuch

[htuch]

Yeah, we should probably do this at some point, let's have the dust settle first. #16274 stopped users doing anything dangerous here, so I think maybe clean this one up after next release.

[github-actions]

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[daixiang0]

Still available?

[htuch]

Sure

[daixiang0]

Yeah, we should probably do this at some point, let's have the dust settle first. #16274 stopped users doing anything dangerous here, so I think maybe clean this one up after next release.

Is time to clean it? If so, I would like to take.

[htuch]

If you want to work on the PR, we can merge it after 1.19 ships in early July.

[daixiang0]

got, would do it after 1.19.

/assign

[jpeach]

Will this option make sense again as the v4 API matures?

[htuch]

@jpeach postmortem pending, but I think based on v2 -> v3 experiences, v4 is very far away (at least multiple years) if it happens at all.

[htuch]

Fixed in #17724