GlFilteredSearch: Apply label color to token in Analytics space

We implemented a shared label token for the Analytics team for GlFilteredSearch in !30706 (merged).

Currently, label tokens have the same color as any other token. Let's use the label's color (which we receive from the API) and apply it as background color to the token. This is how the legacy component display label tokens:

Eventually, the shared label token should look the same as ☝

Note: This is currently blocked by gitlab-ui#811 (closed)