[SalesForce] Lightning quick action modal styling of background using SLDS

What you all need is implement one interface in component i.e. force:lightningQuickActionWithoutHeader.

Components that implement the force:lightningQuickActionWithoutHeader interface display in a panel without additional controls and are expected to provide a complete user interface for the action.

When used as actions, components that implement the force:lightningQuickAction interface display in a panel with standard action controls, such as a Cancel button. These components can also display and implement their own controls but should be prepared for events from the standard controls.

And in your controller, you can use this var dismissActionPanel = $A.get("e.force:closeQuickAction"); dismissActionPanel.fire();

({
    doInit : function(component, event, helper) {
        var action = component.get("c.cloneOpportunity");
        var opp = component.get("v.recordId");
        action.setParams({
                "OppId" : component.get("v.recordId")
                });
        action.setCallback(this,function(data){
           var clonedRecordId = data.getReturnValue();        
             helper.navigate(component);
            var dismissActionPanel = $A.get("e.force:closeQuickAction");
             dismissActionPanel.fire();

        });
 $A.enqueueAction(action);
 }
})

Note:-

When used as actions, components that implement the force:lightningQuickAction interface display in a panel with standard action controls, such as a Cancel button. These components can also display and implement their own controls, but should be prepared for events from the standard controls.

Components that implement the force:lightningQuickActionWithoutHeader interface display in a panel without additional controls and are expected to provide a complete user interface for the action.

These interfaces are mutually exclusive. That is, components can implement either the force:lightningQuickAction interface or the force:lightningQuickActionWithoutHeader interface, but not both. This should make sense; a component can’t both present standard user interface elements and not present standard user interface elements.

Reference:-

1. https://releasenotes.docs.salesforce.com/en-us/winter17/release-notes/rn_lightning_component_actions.htm
2. https://developer.salesforce.com/docs/atlas.en-us.204.0.lightning.meta/lightning/components_using_lex_s1_config_action.htm

Update:-

try this:- you were using $A.get("e.force:closeQuickAction") not on the right place

({
    doInit : function(component, event, helper) {

        var action = component.get("c.getRecordTypeId");
        action.setParams({
            accountId : component.get("v.recordId")
        });
        action.setCallback(this, function(response){
            var state = response.getState();
            if(state === "SUCCESS"){
                var recordTypeId = response.getReturnValue();
                helper.navigate(component);
                var dismissActionPanel = $A.get("e.force:closeQuickAction");
                dismissActionPanel.fire();
            }
            else if(state === "ERROR"){
                console.log('Error: ' + JSON.stringify(response.error));
            }
                else {
                console.log('Unknown problem, state: '+ state + ', error: ' + JSON.stringify(response.error));
            }
        });

        $A.enqueueAction(action);
    }
})

Helper class:-

({
    navigate : function(component, optyId) {
        var createRecordEvent = $A.get("e.force:createRecord");
        createRecordEvent.setParams({
            "recordId": component.get("v.recordId"),
            "entityApiName": "Opportunity",
            "defaultFieldValues": {
                'AccountId' : component.get("v.recordId")
            }
        });      
        createRecordEvent.fire();
    }
})

Not quite there. force:hasRecordId will populate an attribute named recordId with your data, but nothing else. It's on you to query the fields you want out of that record (or use recordEdit/recordView)

When your component is invoked in a record context in Lightning Experience or the Salesforce app, the recordId is set to the ID of the record being viewed.

Also, beware of the below

Important The recordId attribute is set only when you place or invoke the component in an explicit record context. For example, when you place the component directly on a record page layout, or invoke it as an object-specific action from a record page or object home. In all other cases, such as when you invoke the component as a global action, or create the component programmatically inside another component, recordId isn’t set, and your component shouldn’t depend on it.

Full Documentation is here