feat: Update transaction.proto to include different lock modes (#2112)

* feat: Update transaction.proto to include different lock modes PiperOrigin-RevId: 481838475 Source-Link: googleapis/googleapis@922f1f3 Source-Link: https://github.com/googleapis/googleapis-gen/commit/bf32c6e413d4d7fd3c99b725fab653eb983d9dd6 Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiYmYzMmM2ZTQxM2Q0ZDdmZDNjOTliNzI1ZmFiNjUzZWI5ODNkOWRkNiJ9 * 🦉 Updates from OwlBot post-processor See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

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