pytest: use dante-server in CI

- add startup check for 'danted' to avoid fails on low cpu
- rename 'sockd' to 'danted' everywhere to clarify what we use
- add proper defaults for 'danted' for debian
- install 'dante-server' in pytest ci runs

Closes #18075

.github/workflows/http3-linux.yml

@@ -151,7 +151,7 @@ jobs:
             nettle-dev libp11-kit-dev libtspi-dev libunistring-dev guile-2.2-dev libtasn1-bin \
             libtasn1-6-dev libidn2-0-dev gawk gperf libtss2-dev dns-root-data bison gtk-doc-tools \
             texinfo texlive texlive-extra-utils autopoint libev-dev \
-            apache2 apache2-dev libnghttp2-dev
+            apache2 apache2-dev libnghttp2-dev dante-server
           echo 'CC=gcc-12' >> "$GITHUB_ENV"
           echo 'CXX=g++-12' >> "$GITHUB_ENV"
 
@@ -343,7 +343,7 @@ jobs:
             nettle-dev libp11-kit-dev libtspi-dev libunistring-dev guile-2.2-dev libtasn1-bin \
             libtasn1-6-dev libidn2-0-dev gawk gperf libtss2-dev dns-root-data bison gtk-doc-tools \
             texinfo texlive texlive-extra-utils autopoint libev-dev libuv1-dev \
-            apache2 apache2-dev libnghttp2-dev vsftpd
+            apache2 apache2-dev libnghttp2-dev vsftpd dante-server
           python3 -m venv ~/venv
           echo 'CC=gcc-12' >> "$GITHUB_ENV"
           echo 'CXX=g++-12' >> "$GITHUB_ENV"

.github/workflows/linux.yml

@@ -288,7 +288,7 @@ jobs:
         env:
           INSTALL_PACKAGES: >-
             ${{ !contains(matrix.build.install_steps, 'skipall') && !contains(matrix.build.install_steps, 'skiprun') && 'stunnel4' || '' }}
-            ${{ contains(matrix.build.install_steps, 'pytest') && 'apache2 apache2-dev libnghttp2-dev vsftpd' || '' }}
+            ${{ contains(matrix.build.install_steps, 'pytest') && 'apache2 apache2-dev libnghttp2-dev vsftpd dante-server' || '' }}
 
         run: |
           sudo rm -f /etc/apt/sources.list.d/microsoft-prod.list