test: migrate e2e/mint to system tests (backport #22294)

[mergify]

Description

Closes: #22291

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Author Checklist

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I have...

• included the correct type prefix in the PR title, you can find examples of the prefixes below:

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• included the necessary unit and integration tests

• added a changelog entry to CHANGELOG.md

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• confirmed the correct type prefix in the PR title
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• reviewed state machine logic, API design and naming, documentation is accurate, tests and test coverage

Summary by CodeRabbit

• New Features

  • Introduced a new system test suite for minting-related gRPC queries, validating mint parameters and inflation rates.

• Bug Fixes

  • Removed outdated end-to-end test files that were no longer necessary for the mint module.

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This is an automatic backport of pull request #22294 done by [Mergify](https://mergify.com).