Disable self-signed Windows signing for now

Not sure what's wrong with it, either something weird with the runner or
it's expired or something. Not that relevant anymore given that we have
SignPath now though.

.github/workflows/main.yml

@@ -491,19 +491,6 @@ jobs:
           key: gradle-${{ runner.os }}-${{ matrix.arch }}+${{ matrix.cross_os }}-${{ matrix.qt }}
         if: matrix.cross_os == 'Android'
 
-      - name: Prepare local Windows signing for builds not using SignPath
-        run: |
-          if ($env:WINDOWS_CERTIFICATE) {
-            New-Item -ItemType directory -Path "$env:GITHUB_WORKSPACE/wincert"
-            Set-Content -Path "$env:GITHUB_WORKSPACE/wincert/drawpile.txt" -Value $env:WINDOWS_CERTIFICATE
-            certutil -decode "$env:GITHUB_WORKSPACE/wincert/drawpile.txt" "$env:GITHUB_WORKSPACE/wincert/drawpile.pfx"
-            Remove-Item -Path "$env:GITHUB_WORKSPACE/wincert/drawpile.txt"
-            echo "WINDOWS_PFX_PATH=$env:GITHUB_WORKSPACE/wincert/drawpile.pfx" >>$env:GITHUB_ENV
-          }
-        env:
-          WINDOWS_CERTIFICATE: ${{ secrets.WINDOWS_CERTIFICATE }}
-        if: runner.os == 'Windows' && matrix.packager && (!startsWith(github.ref, 'refs/tags/') || !matrix.signpath)
-
       - name: Figure out Windows product version from build version
         run: >
           cmake
@@ -581,8 +568,6 @@ jobs:
           SCCACHE_DIR: ${{ steps.sccache.outputs.path }}/cache
           QT_ANDROID_KEYSTORE_ALIAS: drawpile
           QT_ANDROID_KEYSTORE_STORE_PASS: ${{ secrets.ANDROID_KEYSTORE_PASS }}
-          WINDOWS_PFX_PASS: ${{ secrets.WINDOWS_CERTIFICATE_PASS }}
-          WINDOWS_PFX_TIMESTAMP_URL: 'http://timestamp.digicert.com'
 
       - name: Set PE metadata built files on Windows
         run: >
@@ -602,9 +587,6 @@ jobs:
 
       - name: Run packaging
         run: ${{ matrix.packager }}
-        env:
-          WINDOWS_PFX_PASS: ${{ secrets.WINDOWS_CERTIFICATE_PASS }}
-          WINDOWS_PFX_TIMESTAMP_URL: 'http://timestamp.digicert.com'
         if: matrix.packager
 
       - name: Upload artifacts for SignPath to sign