fix(svm): L-09 close instruction_params account after execute_relayer_refund_leaf

[Reinis-FRP]

OZ identified following issue:

The instruction_params account used in the ExecuteRelayerRefundLeaf instruction remains open after execution,
despite becoming unnecessary once the instruction completes. Leaving the account open leads to resource
inefficiencies. Although a close_instruction_params function can address this issue, it introduces
unnecessary complexity. A more elegant and efficient approach is to leverage Anchor's close attribute to
handle account closure automatically. Unclosed accounts within Solana persist on-chain indefinitely, wasting
storage resources and keeping the lamports from rent locked and unavailable for other operations.

Consider using Anchor's close attribute to ensure that the instruction_params account is automatically
closed, reclaiming resources and simplifying the code.

This PR addresses the issue by closing instruction_params account at the end of execute_relayer_refund_leaf instruction.

[linear]

ACX-3589 L-09 `instruction_params` Account Remains Open After Execution

[chrismaree]

Looks good. can you add a test to show it's closed correctly?

[Reinis-FRP]

Looks good. can you add a test to show it's closed correctly?

Sure, added the check in 71aac65