feat: Replace alertMixin usage with useAlert (#9793)

# Pull Request Template

## Description

This PR will replace the usage of `alertMixin` from the code base with
the `useAlert` composable.

Fixes
https://linear.app/chatwoot/issue/CW-3462/replace-alertmixin-usage-with-usealert

## Type of change

- [x] Breaking change (fix or feature that would cause existing
functionality not to work as expected)

## How Has This Been Tested?

Please refer this issue description

https://linear.app/chatwoot/issue/CW-3462/replace-alertmixin-usage-with-usealert


## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>

app/javascript/dashboard/components/widgets/conversation/ConversationCard.vue

@@ -125,7 +125,6 @@ import { frontendURL, conversationUrl } from '../../../helper/URLHelper';
 import InboxName from '../InboxName.vue';
 import inboxMixin from 'shared/mixins/inboxMixin';
 import ConversationContextMenu from './contextMenu/Index.vue';
-import alertMixin from 'shared/mixins/alertMixin';
 import TimeAgo from 'dashboard/components/ui/TimeAgo.vue';
 import CardLabels from './conversationCardComponents/CardLabels.vue';
 import PriorityMark from './PriorityMark.vue';
@@ -142,8 +141,7 @@ export default {
     PriorityMark,
     SLACardLabel,
   },
-
-  mixins: [inboxMixin, conversationMixin, alertMixin],
+  mixins: [inboxMixin, conversationMixin],
   props: {
     activeLabel: {
       type: String,