ci: Move run_functional_tests into ci-windows-cross.py

This is mostly a refactor, except for putting the temp dirs into
Path.cwd(), which makes running this locally easier.

Note, the use of process_cpu_count() is intentional. It was only added
in Python 3.13, according to
https://docs.python.org/3/library/os.html#os.process_cpu_count .

However, Python 3.13 is also the minimum required version on Windows,
according to
https://github.com/bitcoin/bitcoin/issues/29897#issuecomment-2940318094
to avoid intermittent test failures.

.github/workflows/ci.yml

@@ -435,17 +435,9 @@ jobs:
 
       - name: Run functional tests
         env:
-          TEST_RUNNER_EXTRA: ${{ github.event_name != 'pull_request' && '--extended' || '' }}
+          TEST_RUNNER_EXTRA: "--timeout-factor=${{ env.TEST_RUNNER_TIMEOUT_FACTOR }} ${{ case(github.event_name == 'pull_request', '', '--extended') }}"
         run: |
-          py -3 test/functional/test_runner.py --jobs $NUMBER_OF_PROCESSORS --quiet --tmpdirprefix="$RUNNER_TEMP" --combinedlogslen=99999999 --timeout-factor=$TEST_RUNNER_TIMEOUT_FACTOR $TEST_RUNNER_EXTRA \
-            `# feature_unsupported_utxo_db.py fails on Windows because of emojis in the test data directory.` \
-            --exclude feature_unsupported_utxo_db.py \
-            `# See https://github.com/bitcoin/bitcoin/issues/31409.` \
-            --exclude wallet_multiwallet.py
-          # Run feature_unsupported_utxo_db sequentially in ASCII-only tmp dir,
-          # because it is excluded above due to lack of UTF-8 support in the
-          # ancient release.
-          py -3 test/functional/feature_unsupported_utxo_db.py --previous-releases --tmpdir="${RUNNER_TEMP}/test_feature_unsupported_utxo_db"
+          py -3 .github/ci-windows-cross.py run_functional_tests
 
   ci-matrix:
     name: ${{ matrix.name }}