Sanity checks for Kea 1.9.11 rc1

Please verify the packages and files according to "4. Sanity Checks" chapter on:
    https://wiki.isc.org/bin/view/QA/KeaReleaseProcess#4.%20Sanity%20Checks
and your imagination.
Before starting any checks, please state what check you are doing in a
thread/discussion (not as comment) in Sanity Checks issue in GitLab:
    
When you finish given check state in the same thread/discussion what is the result.
This way we know what is covered upfront and we can avoid repeating ourselves.

Release content is located on:
1) [tarballs] repo.isc.org in the following folders:
   /data/shared/sweng/kea/releases/1.9.11-rc1
   /data/shared/sweng/kea/releases/premium-1.9.11-rc1
   /data/shared/sweng/kea/releases/subscription-1.9.11-rc1

SHA256 (kea-1.9.11.tar.gz) = e594f9cd7f9e1f5c6a29270092ede00ce5750b0fcc8e8ec23f61ca2634004c8e
SHA256 (kea-premium-1.9.11.tar.gz) = a9841c1109cc0a8863dadad8e14cf812ac976ad4ae15677404b77423d6636b3b
SHA256 (kea-subscription-1.9.11.tar.gz) = 13ab698d8af5ee02698fa3cdaafbfa1ce06cd572f72fa02011e76a730260775c

2) [rpm/deb packages] on packages.isc.org, exact packages versions are stored here:
    https://jenkins.aws.isc.org/job/kea-dev/job/pkg/508/
    Release version is 1.9.11-r20210827141637 (please verify if it is this version while installing).
    Install instruction is here: https://wiki.isc.org/bin/view/QA/KeaReleaseProcess, chapter 4. Sanity Checks, point 9.