Improve workflow for people who push "main" in their forks

When people are working`main` branch in their fork, the Github Actions for `canary` build kick in on their fork and fail.

We should likely improve it:

* make it **not fail** and work as expected (should be possible now when we have no pull_request_target - the thing we need is we should always pull some thigns (like branches and tags) from "apache" repo during the build - not from "current" repo
* or fail it quickly and let the user know that they should generally create a branch and work on their branches when they want to submit PR