Add support for Watchguard Firewall X750e

See merge request !8

when running opkg update, this currently results in errors like this:

Downloading https://downloads.openwrt.org/releases/22.03-SNAPSHOT/packages/arm_cortex-a7_neon-vfpv4/base/Packages.gz
wget: SSL support not available, please install one of the libustream-.*[ssl|tls] packages as well as the ca-bundle and ca-certificates packages.
*** Failed to download the package list from https://downloads.openwrt.org/releases/22.03-SNAPSHOT/packages/arm_cortex-a7_neon-vfpv4/base/Packages.gz

since we already have wolfssl for hostapd stuff, just install
libustream-wolfssl and ca-certificates.

Build fails with it, let's see if we need it.

Sometimes, there are untracked files left in the dl directory, which
another job already commited in the DL cache. git pull will then fail
becaue it won't overwrite untracked files.

By first pulling (which will fail), then commiting and pulling again we
will avoid this situation.

Another build job might since have commited its dl-cache hence do a pull
before we commit our dl cache.

Makefile:32: *** Warning: GLUON_BRANCH has been deprecated, please set GLUON_AUTOUPDATER_BRANCH and GLUON_AUTOUPDATER_ENABLED instead.

So let's use the new variables now.

The git push in after_script didn't succeed because of failing
authentication. As the authentication succeeds in before_script, it is
likely the SSH agent from before_script doesn't run in after_script.
Likely because a new shell is spawned. Hence, start it again in
after_script.