refactor(router): refactor relay flow addressing comments of /relay feature pr

[ShankarSinghC]

Type of Change

• Bugfix
• New feature
• Enhancement
• Refactoring
• Dependency updates
• Documentation
• CI/CD

Description

relay feature pr #6879

This PR refactors the relay flow to address the comments from the relay feature PR

Additional Changes

• This PR modifies the API contract
• This PR modifies the database schema
• This PR modifies application configuration/environment variables

Motivation and Context

How did you test it?

Checklist

• I formatted the code cargo +nightly fmt --all
• I addressed lints thrown by cargo clippy
• I reviewed the submitted code
• I added unit tests for my changes where possible

[semanticdiff-com]

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Changed Files

File	Status
crates/hyperswitch_domain_models/src/relay.rs	0% smaller
crates/router/src/core/payments.rs	0% smaller
crates/router/src/core/payments/helpers.rs	0% smaller
crates/router/src/core/payments/transformers.rs	0% smaller
crates/router/src/core/relay/utils.rs	0% smaller
crates/router/src/core/utils.rs	0% smaller
migrations/2024-12-30-072943_remove_defaults_timestamp_in_relay/down.sql	Unsupported file format
migrations/2024-12-30-072943_remove_defaults_timestamp_in_relay/up.sql	Unsupported file format