Merge bitcoin/bitcoin#28567: ci: Only run functional tests on native windows in master

aba4a5887b ci: Only run functional tests on windows in master (Fabian Jahr)

Pull request description:

  This idea was discussed [here](https://github.com/bitcoin/bitcoin/pull/28509#issuecomment-1740841988).

ACKs for top commit:
  hebasto:
    ACK aba4a5887b

Tree-SHA512: 89fd6352b585bae3538d5350b0404c216a8225fe356d408c1ebe3394e7b9a190d65639f4eef310056e020909928d7a1f2de25585c97d2ac087d1a9f72af281eb

.github/workflows/ci.yml

@@ -286,6 +286,10 @@ jobs:
         run: py -3 test\util\rpcauth-test.py
 
       - name: Run functional tests
-        env:
-          TEST_RUNNER_EXTRA: ${{ github.event_name != 'pull_request' && '--extended' || '' }}
-        run: py -3 test\functional\test_runner.py --jobs $env:NUMBER_OF_PROCESSORS --ci --quiet --tmpdirprefix=$env:RUNNER_TEMP --combinedlogslen=99999999 --timeout-factor=$env:TEST_RUNNER_TIMEOUT_FACTOR $env:TEST_RUNNER_EXTRA
+        # Don't run functional tests for pull requests.
+        # The test suit regularly fails to complete in windows native github
+        # actions as a child process stops making progress. The root cause has
+        # not yet been determined.
+        # Discussed in https://github.com/bitcoin/bitcoin/pull/28509
+        if: github.event_name != 'pull_request'
+        run: py -3 test\functional\test_runner.py --jobs $env:NUMBER_OF_PROCESSORS --ci --quiet --tmpdirprefix=$env:RUNNER_TEMP --combinedlogslen=99999999 --timeout-factor=$env:TEST_RUNNER_TIMEOUT_FACTOR --extended