Merge cockroachdb#135693

135693: sql/importer: avoid pointless rand read for imported uuids r=dt a=dt

Imported UUIDs are replaced with deterministic UUIDs to enable resuming imports. Previously however, the in-memory UUID with this deterministic UUID was made by making a random UUID -- reading random numbers from system entropy -- and then replacing what it read with the deterministic numbers.

This skips the epensive and pointless init and just makes an empty struct for the deterministic numbers to be set in.

Release note: none.
Epic: none.

Co-authored-by: David Taylor <[email protected]>

pkg/sql/row/expr_walker.go

@@ -274,7 +274,7 @@ func importGenUUID(
 		c.randSource = makeImportRand(c)
 	}
 	gen := c.randSource.Int63(c)
-	id := uuid.MakeV4()
+	id := uuid.UUID{}
 	id.DeterministicV4(uint64(gen), uint64(1<<63))
 	return tree.NewDUuid(tree.DUuid{UUID: id}), nil
 }