[table] increase min width for filterable columns

[bjornalm]

What package is this for?

• [x] React
• [ ] Angular

Summary

There should always be text visible in the dropdowns of filterable columns, so we need to increase the column min width.

Additional context See discussion here https://github.com/carbon-design-system/carbon-addons-iot-react/issues/3231#issuecomment-1046976564

This is how it currently can look

Specific timeline issues / requests

Do you want this work within a specific time period? Is it related to an upcoming release?

NB: The core contributors will try to work with your timeline, but it's not guaranteed. The earlier you make a request in advance of a desired delivery date, the better!

Available extra resources

What resources do you have to assist this effort?

Carbon add-ons for Watson IoT is a collaborative system. We encourage teams to build components and submit them for integration.