avoid index-of-bounds panics in SetAnnotation in production

[bghal]

This complementary issue was addressed on the GetAnnotation side in #151849.

If the AnnotatedNode.AnnIdx=NoAnnotation (0), the adjustment from 1-based indexing to 0-based indexing induces a panic. The upper-bound may also have the same issue the getter had.

tableName := tree.TableName{ObjectName: "foo"}
planner.ResolveExistingObjectEx(ctx, tableName.ToUnresolvedObjectName(), true /* required */, tree.ResolveRequireTableDesc)

Jira issue: CRDB-55425

[blathers-crl]

Hi @bghal, please add a branch-* label to identify the earliest affected branch for this C-bug

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[yuzefovich]

I don't think this is an actual issue, closing.