sql: add COPY to sampled_query logging

[otan]

As requested by product, we want COPY to show up on sampled_query. This
commit adds this, whilst fudging a few things presumably more relevant
to "regular" DDL statements.

Release justification: telemetry only change

Release note: None

[cockroach-teamcity]

This change is 

[cucaroach]

Reviewed 2 of 3 files at r1.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @cucaroach)

[otan]

bors r=cucaroach

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)

[blathers-crl]

Encountered an error creating backports. Some common things that can go wrong:

1. The backport branch might have already existed.
2. There was a merge conflict.
3. The backport branch contained merge commits.

You might need to create your backport manually using the backport tool.

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error creating merge commit from 5f24073 to blathers/backport-release-21.2-86627: POST https://api.github.com/repos/cockroachdb/cockroach/merges: 409 Merge conflict []

you may need to manually resolve merge conflicts with the backport tool.

Backport to branch 21.2.x failed. See errors above.

---

error creating merge commit from 5f24073 to blathers/backport-release-22.1-86627: POST https://api.github.com/repos/cockroachdb/cockroach/merges: 409 Merge conflict []

you may need to manually resolve merge conflicts with the backport tool.

Backport to branch 22.1.x failed. See errors above.

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