ci: skip FreeBSD/macOS jobs in a fork

When I added these workflows (tarantool#13246, tarantool#13247), I had two points in the
head:

* I don't want to bloat the workflows with many rules where and when to
  run. Instead, I want them to be tiny wrappers around commands they're
  run.
* The workflows are able to run in forks and it may be useful for
  debugging purposes.

All the other workflows are disabled in the forks, mainly because they
use self-hosted runners and secrets (tarantool#6913). This is not the case here.

However, I found that I don't like that something is run in my fork by
default, because it only spend resources, while I anyway look for the
status in a pull request. The fork works are a bucket of branches for
me, nothing over that.

Let's skip the runs in forks.

It is still possible to perform debugging on the runners using these
workflows in a fork, but now it requires a manual action: drop the `if`
clauses.

NO_DOC=ci
NO_CHANGELOG=ci
NO_TEST=ci

Author: Totktonada

.github/workflows/freebsd.yml

@@ -7,12 +7,19 @@ permissions:
 
 jobs:
   freebsd:
-    # Run on a branch push and on a pull request from a fork. A pull request
-    # from a branch of this repository is tested by the push of that branch.
+    # | Event                                 | Runs?  |
+    # | ------------------------------------- | ------ |
+    # | Push a branch to a fork               | no     |
+    # | Push a branch to tarantool/tarantool  | yes    |
+    # | Pull request from a fork              | yes    |
+    # | Pull request from tarantool/tarantool | no[^1] |
+    #
+    # [^1]: Branch push status is shown in the pull request in the case.
     if: |
-      github.event_name == 'push' ||
-      github.event_name == 'pull_request' &&
-      github.event.pull_request.head.repo.full_name != github.repository
+      github.repository_owner == 'tarantool' && (
+        github.event_name == 'push' ||
+        github.event_name == 'pull_request' &&
+        github.event.pull_request.head.repo.full_name != github.repository)
 
     # ubuntu-latest will be 26.04 soon. Switch ahead of time.
     #

.github/workflows/macos.yml

@@ -4,11 +4,19 @@ on: [push, pull_request]
 
 jobs:
   macos:
-    # Run on a branch push and on a pull request from a fork. A pull request
-    # from a branch of this repository is tested by the push of that branch.
-    if: github.event_name == 'push' ||
+    # | Event                                 | Runs?  |
+    # | ------------------------------------- | ------ |
+    # | Push a branch to a fork               | no     |
+    # | Push a branch to tarantool/tarantool  | yes    |
+    # | Pull request from a fork              | yes    |
+    # | Pull request from tarantool/tarantool | no[^1] |
+    #
+    # [^1]: Branch push status is shown in the pull request in the case.
+    if: |
+      github.repository_owner == 'tarantool' && (
+        github.event_name == 'push' ||
         github.event_name == 'pull_request' &&
-        github.event.pull_request.head.repo.full_name != github.repository
+        github.event.pull_request.head.repo.full_name != github.repository)
 
     runs-on: macos-latest