Use separate configurations for stable and feature branches

[NickVolynkin]

In some repositories like tarantool/tarantool-ee we need the following settings:

• On master and other stable branches, restart jobs as usual
• Same for RPs on feature branches, where commits are made by humans
• Ignore failed jobs in integration PRs, because they almost never fail because of flaky tests; it's always some stable test failure.

We need to support such behaviour somewhere in the service's configuration. It could be something like the syntax of GitHub workflows' branch selection.