tests(mint): more test coverage for mint

[hoangdv2429]

PR Standards

Opening a pull request should be able to meet the following requirements

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Table style test scenario and more test cases.

For Author:

• Targeted PR against correct branch
• included the correct type prefix in the PR title
• Linked to Github issue with discussion and accepted design
• Targets only one github issue
• Wrote unit and integration tests
• All CI checks have passed
• Added relevant godoc comments

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For Reviewer:

• confirmed the correct type prefix in the PR title
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After reviewer approval:

• In case targets main branch, PR should be squashed and merged.
• In case PR targets a release branch, PR should be rebased.

[omritoptix]

seems like currently we're only testing if the after epoch end coins were minted but we don't actually check the amount is the expected amount

[hoangdv2429]

I think this one cover the minting amount https://github.com/decentrio/dymension-rdk/blob/d1879871eda9f7b3a8af0b8364caed9c4c2aef50/x/mint/keeper/mint_test.go#L20-L21. But I agree we should also check the minting amount here as well