fix(VAutoComplete): v auto complete does not hide placeholder when multiple property is defined

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Description

Hide placeholder in VAutoComplete component when multiple property is defiend and at least one item is selected.
I solve it using isDirty value in VTextField component.

fixes #16519

Markup:

<template>
  <v-app>
    <v-main>
         <v-autocomplete
            v-model="values"
            :items="items"
            placeholder="Select Item"
            multiple
          ></v-autocomplete>
    </v-main>
  </v-app>
</template>
<script>
  export default {
    data: () => ({
      items: ['foo', 'bar', 'fizz', 'buzz'],
      values: ['foo', 'bar'],
    }),
  }
</script>

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See #16565.