ZKsync bridges are outdated

In [this page](https://github.com/MetaMask/metamask-docs/blob/main/services/reference/zksync/json-rpc-methods/zks_getbridgecontracts.mdx) the method does not include the new shared bridges. Also mentioned legacy bridge is being deprecated as detailed here: https://github.com/zkSync-Community-Hub/zksync-developers/discussions/998

Update services/reference/zksync/json-rpc-methods/zks_getbridgecontracts.mdx. First compare the current method documentation with the linked ZKsync discussion, then confirm the shared bridges and legacy-bridge deprecation details. Done means the page accurately reflects the current bridge set and status; no tests are mentioned in the issue.

Written by the indexing model from the issue text.