GHA: use more ninja, build examples in the last step, and more

- linux: bump up test parallelism for valgrind tests to `-j4`
  (from `-j2`). (EXPERIMENTAL)
- linux: drop `apt-get update` for the default architecture on the GHA
  native runner. It makes prereq install steps complete faster.
  The runner image gets weekly updates, and that should be enough to
  guarantee fresh packages in most cases:
  https://github.com/actions/runner-images/commits/main/images/ubuntu/Ubuntu2204-Readme.md
- aws-lc: use ninja with cmake.
- aws-lc: build examples with cmake.
- aws-lc: drop `apt update`.
- aws-lc, wolfssl, linux32, http3-linux: move building examples to
  the last step.
  Follow-up to 45202cbba4 #14906
- windows: formatting.

Closes #14992

.github/workflows/linux.yml

@@ -250,8 +250,6 @@ jobs:
     steps:
       - if: matrix.build.container == null
         run: |
-          sudo rm -f /etc/apt/sources.list.d/microsoft-prod.list
-          sudo apt-get update
           sudo apt-get install libtool autoconf automake pkgconf stunnel4 libpsl-dev libbrotli-dev libzstd-dev ${{ matrix.build.install_packages }}
           sudo python3 -m pip install impacket
         name: 'install prereqs and impacket'
@@ -550,6 +548,9 @@ jobs:
         timeout-minutes: ${{ contains(matrix.build.install_packages, 'valgrind') && 30 || 15 }}
         run: |
           export TFLAGS='${{ matrix.build.tflags }}'
+          if [[ '${{ matrix.build.install_packages }}' = *'valgrind'* ]]; then
+            TFLAGS+=' -j4'
+          fi
           if [[ '${{ matrix.build.install_packages }}' = *'heimdal-dev'* ]]; then
             TFLAGS+=' ~2077 ~2078'  # valgrind errors
           fi