amber-jobs: Use http URI for amber-phone repos

Otherwise initial apt-get update fails because of missing ca-certificates.
4 jobs for http in 1 minute and 42 seconds (queued for 1 minute and 57 seconds)
Status Job ID Name Coverage
  Test
passed #321868
librem5
test:native

00:00:15

 
  Package
passed #321869
librem5
package-debian-buster

00:00:52

 
  Test Package
passed #321870
librem5
autopkgtest-debian-buster-package

00:00:31

passed #321871
librem5
lintian-debian-buster-package

00:00:34