database: simplify tpk_to_string

Use the convenience function to armor certificates.  This also adds
comments to the armor blocks, making it easier to identify
certificates when casually inspecting them as text files.
1 job for justus/fixes in 12 minutes and 48 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Build
passed #1044035449
docker
build:binary

00:12:48