Data pages use indicator tag data when chart tag data is present

[ikesau]

Problem

Slack context

In the living languages data page, no tags are shown, despite the chart being tagged with 2 tags in the admin.

This is due to the ETL indicator data tagging the indicator as "Uncategorized", which according to Lucas, is to indicate that the data managers aren't sure how to categorize the data.

I fixed the dangling heading showing up in the data page header, but the fix for this that properly reconciles the two sources of truth will take a bit more effort.

Impact

Presumably a number of data pages are missing tags, which has the effect of removes topic page links on the top right of the data pages, so slightly worse navigation.

Proposed solution

Probably the union of chart and indicator tags excluding Uncategorized.