Scale production properly

[xtremerui]

With less PRs to run and reduced topgun jobs (removed from releasing pipelines), and also less releasing pipelines, it should be able to cut pr workers from 3 to 1 and general workers from 8 to 4.

Below are workers list atm:

administrators-Mac-mini.local         6           darwin    none        main  running  2.4      8d
c90d0f30-76f8-41a5-b10b-22b006356d13  10          linux     bosh        main  running  2.4      29m23s
ci-pr-worker-0                        13          linux     pr          none  running  2.4      1d
ci-pr-worker-1                        15          linux     pr          none  running  2.4      1d
ci-pr-worker-2                        18          linux     pr          none  running  2.4      1d
ci-workers-worker-0                   58          linux     none        none  running  2.4      1d
ci-workers-worker-1                   56          linux     none        none  running  2.4      1d
ci-workers-worker-2                   55          linux     none        none  running  2.4      1d
ci-workers-worker-3                   86          linux     none        none  running  2.4      1d
ci-workers-worker-4                   71          linux     none        none  running  2.4      1d
ci-workers-worker-5                   67          linux     none        none  running  2.4      1d
ci-workers-worker-6                   55          linux     none        none  running  2.4      1d
ci-workers-worker-7                   71          linux     none        none  running  2.4      1d
topgun-worker-worker-0                0           linux     k8s-topgun  none  running  2.4      1d
windows-worker-ci                     0           windows   none        main  running  2.4      50m42s

[xtremerui]

concourse/prod@04670d9 bosh worker 2 -> 1