AdHocFiltersCombobox: adjust combobox filter values when switching between multi and single operators

[Sergej-Vlasov]

Added special logic for switching between operator multi/single types:

1. switching from multi to single

   • reset local multi value state
   • reset filter values and valueLabels fields

2. switching from single to multi

   • populate local multi value state
   • add default values in filter values and valueLabels fields

📦 Published PR as canary version: 5.20.3--canary.927.11457305359.0

:sparkles: Test out this PR locally via: ```bash npm install @grafana/scenes-react@5.20.3--canary.927.11457305359.0 npm install @grafana/scenes@5.20.3--canary.927.11457305359.0 # or yarn add @grafana/scenes-react@5.20.3--canary.927.11457305359.0 yarn add @grafana/scenes@5.20.3--canary.927.11457305359.0 ```

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:rocket: PR was released in v5.20.3 :rocket: