Merge #606: travis: Remove unused sudo:false

7667532 travis: Remove unused sudo:false (MarcoFalke)

Pull request description:

  Builds in sudo-disabled docker containers are no longer available as of last year and all builds happen on sudo enabled vms.

  Source: https://blog.travis-ci.com/2018-11-19-required-linux-infrastructure-migration#timeline---its-happening-fast

Tree-SHA512: 882585ba4e1596ad34ddf163acecd043da63443fa95653fba63b03dacf3a669128f1ed142527484cc8dab98de341b425425f418b8151cf7303b0e906ae259a9a