storage: stabilize columnar blocks

[jbowens]

Before GA, columnar blocks should be stable.

• Enable columnar blocks using a metamorphic constant.
• storage: malformed key terminator byte (columnar blocks) #133082
• github.com/cockroachdb/pebble/internal/metamorphic: TestMeta failed pebble#4103
• release-24.3: storage: fix KeySeeker.MaterializeUserKey #132951
• Re-enable the cluster setting on release-24.3

Jira issue: CRDB-43502

[blathers-crl]

Hi @jbowens, please add branch-* labels to identify which branch(es) this GA-blocker affects.

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[blathers-crl]

Hi @jbowens, please add a C-ategory label to your issue. Check out the label system docs.

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[RaduBerinde]

It seems like we are still 1-2 weeks away from columnar blocks reliably working on master. To be safe, we have decided to aim for a 24.3.x release for allowing enabling the columnar format. #133082 is removing the cluster setting until then.