Replace virtualenv with Python's built-in venv (#30377)

* Replace virtualenv with Python's built-in venv.

* Apply Delan's suggestions and make a couple small fixes

- Fix a tidy warning about directories that don't exist
- Use shutil instead of the redundant get_exec_path
- Miscellaneous cleanups

* Fix typo in environment variable

* fix bug where pip still tries to the wrong site-packages

---------

Co-authored-by: Martin Robinson <mrobinson@igalia.com>
Co-authored-by: Delan Azabani <dazabani@igalia.com>

.github/workflows/docs.yml

@@ -17,7 +17,7 @@ jobs:
           fetch-depth: 2
       - name: Bootstrap
         run: |
-          python3 -m pip install --upgrade pip virtualenv
+          python3 -m pip install --upgrade pip
           sudo apt update
           python3 ./mach bootstrap
       - name: Compile docs

.github/workflows/linux-wpt.yml

@@ -57,7 +57,7 @@ jobs:
         run: tar -xzf release-binary/target.tar.gz
       - name: Prep test environment
         run: |
-          python3 -m pip install --upgrade pip virtualenv
+          python3 -m pip install --upgrade pip
           sudo apt update
           sudo apt install -qy --no-install-recommends libgl1 libssl1.1 libdbus-1-3 libxcb-xfixes0-dev libxcb-shape0-dev libunwind8 libgl1-mesa-dri mesa-vulkan-drivers libegl1-mesa
           sudo apt install ./libffi6_3.2.1-8_amd64.deb

.github/workflows/linux.yml

@@ -87,7 +87,7 @@ jobs:
           crate: taplo-cli
           locked: true
       - name: Bootstrap Python
-        run: python3 -m pip install --upgrade pip virtualenv
+        run: python3 -m pip install --upgrade pip
       - name: Bootstrap dependencies
         run: sudo apt update && python3 ./mach bootstrap
       - name: Tidy

.github/workflows/mac-wpt.yml

@@ -43,7 +43,7 @@ jobs:
       - name: Prep test environment
         run: |
           gtar -xzf target.tar.gz
-          python3 -m pip install --upgrade pip virtualenv
+          python3 -m pip install --upgrade pip
           python3 ./mach bootstrap
       - name: Smoketest
         run: python3 ./mach smoketest --${{ inputs.profile }}

.github/workflows/mac.yml

@@ -82,7 +82,7 @@ jobs:
           locked: true
       - name: Bootstrap
         run: |
-          python3 -m pip install --upgrade pip virtualenv
+          python3 -m pip install --upgrade pip
           python3 ./mach bootstrap
           brew install gnu-tar
       - name: Build (${{ inputs.profile }})

.github/workflows/nightly-rust.yml

@@ -24,7 +24,7 @@ jobs:
         run: echo nightly > rust-toolchain
       - name: Bootstrap
         run: |
-          python3 -m pip install --upgrade pip virtualenv
+          python3 -m pip install --upgrade pip
           sudo apt update
           python3 ./mach bootstrap
       - name: Release build

.github/workflows/scheduled-wpt-import.yml

@@ -35,7 +35,7 @@ jobs:
       - uses: actions/download-artifact@v3
       - name: Prep environment
         run: |
-          python3 -m pip install --upgrade pip virtualenv
+          python3 -m pip install --upgrade pip
           sudo apt update
           python3 ./mach bootstrap
       - name: Add upstream remote

.github/workflows/windows.yml

@@ -78,7 +78,7 @@ jobs:
           # this point crown is not installed yet.
           RUSTC: "rustc"
         run: |
-          python -m pip install --upgrade pip virtualenv
+          python -m pip install --upgrade pip
           python mach fetch
           python mach bootstrap-gstreamer
           cargo install --path support/crown