Merge bitcoin/bitcoin#28384: ci: Avoid oversubscription in functional tests on Windows

f2d4e510b3 ci: Avoid saving the same Ccache cache (Hennadii Stepanov)
14e5de6d02 ci: Avoid oversubscription in functional tests on Windows (Hennadii Stepanov)

Pull request description:

  This PR aims to reduce the frequency of functional test failures on Windows like this [one](https://github.com/bitcoin/bitcoin/actions/runs/6040229997):
  ```

  2023-09-01T01:05:01.850000Z TestFramework (ERROR): Assertion failed
  Traceback (most recent call last):
    File "D:\a\bitcoin\bitcoin\test\functional\test_framework\test_framework.py", line 552, in start_nodes
      node.wait_for_rpc_connection()
    File "D:\a\bitcoin\bitcoin\test\functional\test_framework\test_node.py", line 296, in wait_for_rpc_connection
      self._raise_assertion_error("Unable to connect to bitcoind after {}s".format(self.rpc_timeout))
    File "D:\a\bitcoin\bitcoin\test\functional\test_framework\test_node.py", line 177, in _raise_assertion_error
      raise AssertionError(self._node_msg(msg))
  AssertionError: [node 1] Unable to connect to bitcoind after 2400s
  ```

  This code has had zero failures in my personal repository in more than 25 runs (and is still counting).

  ---

  The second commit is a minor improvement to avoid "Cache save failed." warnings during job re-runs. For [example](https://github.com/bitcoin/bitcoin/actions/runs/5998688759):

  ![image](https://github.com/bitcoin/bitcoin/assets/32963518/d8a049df-fccd-4395-99c9-4be01d0ea706)

ACKs for top commit:
  MarcoFalke:
    lgtm ACK f2d4e510b3 🐾

Tree-SHA512: 0c92817d37325a114886900e49a4d644201397d98d6ac9f2dcd41170c7e7ea2cb1873f7e51b5cb3ad3cc2e59554ad1c8f87d439ea6c1c960bf5c339153be7040

.github/workflows/ci.yml

@@ -52,6 +52,7 @@ jobs:
         run: echo "CCACHE_DIR=${RUNNER_TEMP}/ccache_dir" >> "$GITHUB_ENV"
 
       - name: Restore Ccache cache
+        id: ccache-cache
         uses: actions/cache/restore@v3
         with:
           path: ${{ env.CCACHE_DIR }}
@@ -63,7 +64,7 @@ jobs:
 
       - name: Save Ccache cache
         uses: actions/cache/save@v3
-        if: github.event_name != 'pull_request'
+        if: github.event_name != 'pull_request' && steps.ccache-cache.outputs.cache-hit != 'true'
         with:
           path: ${{ env.CCACHE_DIR }}
           # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#update-a-cache
@@ -203,6 +204,7 @@ jobs:
           Copy-Item -Path "$env:ChocolateyInstall\lib\ccache\tools\ccache-$env:CI_CCACHE_VERSION-windows-x86_64\ccache.exe" -Destination "C:\ccache\cl.exe"
 
       - name: Restore Ccache cache
+        id: ccache-cache
         uses: actions/cache/restore@v3
         with:
           path: ~/AppData/Local/ccache
@@ -243,7 +245,7 @@ jobs:
 
       - name: Save Ccache cache
         uses: actions/cache/save@v3
-        if: github.event_name != 'pull_request'
+        if: github.event_name != 'pull_request' && steps.ccache-cache.outputs.cache-hit != 'true'
         with:
           path: ~/AppData/Local/ccache
           # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#update-a-cache
@@ -264,5 +266,4 @@ jobs:
       - name: Run functional tests
         env:
           TEST_RUNNER_EXTRA: ${{ github.event_name != 'pull_request' && '--extended' || '' }}
-        shell: cmd
-        run: py -3 test\functional\test_runner.py --ci --quiet --tmpdirprefix=%RUNNER_TEMP% --combinedlogslen=99999999 --timeout-factor=%TEST_RUNNER_TIMEOUT_FACTOR% %TEST_RUNNER_EXTRA%
+        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