fix(defaults): avoid parent config leaking into menu and dialog content

[J-Sek]

fixes #18123

Markup:

// defaults.js
export default {
  VTextField: { variant: 'outlined' },
  VTable: {
    VTextField: { variant: 'solo' },
  },
}

<template>
  <v-app theme="dark">
    <v-container>
      <v-sheet>
        <h2>With No VDefaultsProvider (Expected Code)</h2>
        <v-table>
          <tbody>
            <tr>
              <td>
                <v-text-field placeholder="plain" />
              </td>
              <td>
                <v-dialog>
                  <template #activator="{ props }">
                    <v-btn v-bind="props">Click</v-btn>
                  </template>
                  <v-card width="300">
                    <v-card-text>
                      <v-text-field placeholder="outlined" />
                    </v-card-text>
                  </v-card>
                </v-dialog>
              </td>
            </tr>
          </tbody>
        </v-table>

        <h2>With An Empty VDefaultsProvider (Workaround)</h2>
        <v-defaults-provider :defaults="{}">
          <v-table>
            <tbody>
              <tr>
                <td>
                  <v-text-field placeholder="plain" />
                </td>
                <td>
                  <v-dialog>
                    <template #activator="{ props }">
                      <v-btn v-bind="props">Click</v-btn>
                    </template>
                    <v-card width="300">
                      <v-card-text>
                        <v-text-field placeholder="outlined" />
                      </v-card-text>
                    </v-card>
                  </v-dialog>
                </td>
              </tr>
            </tbody>
          </v-table>
        </v-defaults-provider>
      </v-sheet>
    </v-container>
  </v-app>
</template>

<script setup>
  import { ref } from 'vue'

  const work = ref('it works')
  const notwork = ref('it doesnt work')

  const workItems = ref(['it', 'works', 'fine'])
  const notWorkItems = ref(['it', 'doesnt', 'work'])
</script>