QGB state machine confirm signed by validator

[rach-id]

Summary of Bug

Currently, the QGB queries the validator by orchestrator to check if the validator was registered.
However, this check only checks the current set of validators. Thus, submitting confirms for old valsets can fail even if they are correct:

celestia-app/x/qgb/keeper/msg_server.go

Line 51 in d63b998

validator, found := k.StakingKeeper.GetValidatorByOrchestrator(ctx, orchaddr)

This will need to be fixed.

Version

d63b998

Steps to Reproduce

not needed.

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned

[rach-id]

Following the decision taken on #631, this check will need to be deleted also as we will no longer iterate over valsets