ccl/backupccl: do not backup spans for views

[rhu713]

Backups currently backup spans corresponding to views. These spans should not
be backed up as they do not contain data.

Additionally, because we do not split ranges at view boundaries, it is possible
that the range the view span belongs to is shared by another object in the
cluster (that we may or may not be backing up) that might have its own bespoke
zone configurations, namely one with a short GC TTL. This could lead to a
situation where the short GC TTL on the range we are not backing up causes our
protectedts verification to fail when attempting to backup the view span.

Release note (bug fix): Fix a bug in backup where spans for views were being
backed up. Because ranges are not split at view boundaries, this can cause the
backup to send export requests to ranges that do not belong to any backup
target.

Release justification: bug fixes and low-risk updates to new functionality

[cockroach-teamcity]

This change is 

[rhu713]

Basically the same change as #66072, but I don't think it was ever merged to master.

[rhu713]

bors r+

[craig]

Build failed (retrying...):

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[craig]

Build failed (retrying...):

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[craig]

Build failed (retrying...):

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[craig]

Build succeeded:

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[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 92397cc to blathers/backport-release-21.1-85158: 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 21.1.x failed. See errors above.

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error creating merge commit from 92397cc to blathers/backport-release-21.2-85158: 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.

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error creating merge commit from 92397cc to blathers/backport-release-22.1-85158: 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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