fix: remove duplicated message type events

Description

Currently, the sdk.MessageEventType is emitted twice in Desmos, it is because that cosmos-sdk already handles the default message type event. As we can see, the example transaction has two message type event:

[
    {
        "events": [
            {
                "type": "message",
                "attributes": [
                    {
                        "key": "action",
                        "value": "/desmos.posts.v3.MsgCreatePost"
                    },
                    {
                        "key": "sender",
                        "value": "desmos1q35n50xnlj7lapfkzzcq5rvypcvhure0rr945u"
                    }
                ]
            },
            {
                "type": "message",
                "attributes": [
                    {
                        "key": "module",
                        "value": "posts"
                    },
                    {
                        "key": "action",
                        "value": "/desmos.posts.v3.MsgCreatePost"
                    },
                    {
                        "key": "sender",
                        "value": "desmos1q35n50xnlj7lapfkzzcq5rvypcvhure0rr945u"
                    }
                ]
            },
         ...skip
]

To fix it, we can safely remove the sdk.MessageEventType event inside Desmos modules. References: https://docs.cosmos.network/v0.47/learn/advanced/events#default-events https://github.com/cosmos/cosmos-sdk/blob/v0.47.5/baseapp/baseapp.go#L848

Author Checklist

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I have...

[x] included the correct type prefix in the PR title
[ ] added ! to the type prefix if API or client breaking change
[ ] targeted the correct branch (see PR Targeting)
[ ] provided a link to the relevant issue or specification
[ ] followed the guidelines for building modules
[ ] included the necessary unit and integration tests
[ ] added a changelog entry to CHANGELOG.md
[ ] included comments for documenting Go code
[ ] updated the relevant documentation or specification
[x] reviewed "Files changed" and left comments if necessary
[ ] confirmed all CI checks have passed

Reviewers Checklist

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I have...

[ ] confirmed the correct type prefix in the PR title
[ ] confirmed ! in the type prefix if API or client breaking change
[ ] confirmed all author checklist items have been addressed
[ ] reviewed state machine logic
[ ] reviewed API design and naming
[ ] reviewed documentation is accurate
[ ] reviewed tests and test coverage
[ ] manually tested (if applicable)

desmos-labs / desmos