Remove "default" indicator for adv. key sizes

It's a bit complicated what kleopatra uses as the default
key size as this was only configurable in kleopatra but
nowadays can be configured in GnuPG and we also have
ECC which could also be default. So rather then to
show a wrong default indicator we do not indicate default
anymore.

GnuPG-Bug-Id: T4988
2 jobs for master in 13 minutes and 26 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #56231
build_clazy_clang_tidy

00:13:25

passed #56230
linux kf5-qt5 qt5.12

00:08:53

0.0%