The uniqueColumnValuesStrategy is fired multiple times when opening an Excel Style Filtering

[DiyanDimitrov]

Description

The uniqueColumnValuesStrategy is fired multiple times (for each column) when opening an Excel Style Filtering.

• igniteui-angular version: NA
• browser: NA

Steps to reproduce

1. Open https://codesandbox.io/s/red-sunset-62o18
2. Open the Excel Style filtering dropdown.
3. Look at the console.

Result

'get column data' is printed 5 times.

Expected result

The uniqueColumnValuesStrategy should be called only once.