Fix licenses in less files

[ronja-ui]

Description

Fix licenses in less files to be only once at the start of the file. The license should also use "Browser User Interface for Teragrep" to match with the repository's description.

Use case or motivation behind the feature request

Currently the license in less files gets duplicated when they're compiled into style.less. It's not ideal, because the license should be only once at the start of file.

Related issues

Additional context

[ronja-ui]

One way to fix this is to use just CSS @import. However, we need to check first it's supported in browser versions we also want to support.

[kortemik]

#492 has many references which belogn here. i will add them here as well.

[sryhanen]

No need to save compiled css file to version control after #480