Dashboard filter of nested question shows plain text input, which does not allow multiple values

[flamber]

Describe the bug
Dashboard filter of nested question shows plain text input, which does not allow multiple values

Regression in master compared to 0.40.5.
P1 contender.

To Reproduce

1. Native question > Sample Dataset > SELECT * FROM PRODUCTS - save as "Q1"
2. Click Explore Results - save as "Q2"
3. Add "Q2" to dashboard, add filter "Other categories" and connect to "Q2"."TITLE" ("CATEGORY" not shown is Not all columns of nested question available for Dashboard filter #13186) - save dashboard
4. Try inputting two values into the filter at the same time - ex. Rustic Paper Wallet and Small Marble Shoes
   

Expected behavior
Same behavior as 0.40.5, where it's still a text input (missing dropdown is #12985), but allows multiple values:

Information about your Metabase Installation:
Tested master a31a7d0