GHA: fix and tweak installed packages for http3-linux and Windows-cross

- explicitly install `libldap-dev` to not rely on test-specific packages
  installing it implicitly, to have the same `curl -V` output for each
  TLS backend build pair.
  Follow-up to 0455d8772a #18509

- install `libev-dev` for tests. It's a runtime dependency for
  the local build of `nghttpx`. Missing it made pytest skip 178 tests.
  Also skewing the 'Gain' time. I estimate it to account for 3 minutes,
  making the total gain ~20 minutes.
  Follow-up to 0455d8772a #18509
  (It may be a better solution to disable libev for the local nghttp2
  build, to avoid this hidden dependency.)

- fix quiche jobs to use the local build of `libnghttp2`.

- stop installing the `clang` package for Windows-cross. `clang` and
  `clang-tidy` tools are preinstalled on the Ubuntu 24.04 runner.

Closes #18519

.github/workflows/windows.yml

@@ -721,11 +721,9 @@ jobs:
           - { build: 'cmake'    , compiler: 'clang-tidy' }
     steps:
       - name: 'install packages'
-        env:
-          INSTALL_PACKAGES: ${{ matrix.compiler == 'clang-tidy' && 'clang' || '' }}
         run: |
           sudo rm -f /var/lib/man-db/auto-update
-          sudo apt-get -o Dpkg::Use-Pty=0 install gcc-mingw-w64-x86-64-win32 ${INSTALL_PACKAGES}
+          sudo apt-get -o Dpkg::Use-Pty=0 install gcc-mingw-w64-x86-64-win32
 
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
         with: