chore(kms-connector): grpc poll immediatly if request already sent

[eudelins-zama]

Closes https://github.com/zama-ai/fhevm-internal/issues/534

[Copilot]

Pull Request Overview

This PR implements an optimization to immediately poll for gRPC responses when a request has already been sent to the KMS, rather than attempting to resend it. This is achieved by tracking request state through a new already_sent boolean field.

Key Changes:

• Added already_sent field to track whether a request has been sent to the KMS
• Modified request sending logic to skip resending when already_sent is true
• Updated database schema and queries to persist the already_sent state

Reviewed Changes

Copilot reviewed 9 out of 16 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
kms_response.rs	Updated to pass already_sent=true when marking events as pending after processing responses
gw_event.rs	Added already_sent field to GatewayEvent struct and updated all related functions to handle this field
kms_worker.rs	Changed event parameter to mutable to allow updating already_sent state during processing
processor.rs	Updated trait and implementation signatures to accept mutable event references
kms_client.rs	Implemented logic to conditionally send requests based on already_sent flag and updated error message
simple.rs, parallel.rs	Updated test fixtures to include already_sent: false in expected results
20251027122128_add_already_sent.sql	Migration adding already_sent column to all request tables
20250826111757_keygen_crs.sql	Added error handling for enum type creation to prevent migration failures

Files not reviewed (7)

• kms-connector/.sqlx/query-0c7e1f45677401d5bf8d0dce8849637a4b533c4371b1620f9259529a1bfebc27.json: Language not supported
• kms-connector/.sqlx/query-12d768492b153b53cf4cb6c9f3e66c1940b5f4f6306113ff9648f690f1379240.json: Language not supported
• kms-connector/.sqlx/query-2c1c41025c09656ec4aa9a6e8ee58b52cadbc7039cf07d158f70dfc46b5e06eb.json: Language not supported
• kms-connector/.sqlx/query-976df9ddb90a8496ff6392dce98caffef797e8177193bf4711fafa1aab746040.json: Language not supported
• kms-connector/.sqlx/query-9e6abfc0df77b3587972fc590ee888338d1e9a3d4f2bdb506d8588319adad879.json: Language not supported
• kms-connector/.sqlx/query-ae80f83b6a6f16cd77a8e1a8a177ca8631cf6a17fc91e6f6784d160ceedfcb98.json: Language not supported
• kms-connector/.sqlx/query-f9e4703b71b26e3c08ecb4960d8c9ff833085240442de258975cde391de302a2.json: Language not supported

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[Copilot]

The SQL update statement now sets already_sent alongside under_process = FALSE. This logic seems counterintuitive: when marking an event as pending (not under process), we're setting already_sent which could be either true or false. If already_sent = true, it suggests the request was sent but is now being marked as pending again, potentially for retry. Consider adding a comment explaining this behavior, as the relationship between 'pending' and 'already_sent' is not immediately clear.

[eudelins-zama]

Replaced by #1241