[PSM Interop] Remove PSM interop github workflow (#35507)

Moved to
270307afe0/.github/workflows/psm-interop.yaml.

This created as a companion to #35466 to split out github-only files
change go/github-only-files-grpc.

.github/workflows/psm-interop.yaml

@@ -1,73 +0,0 @@
-name: PSM Interop
-
-on:
-  pull_request:
-  push:
-    branches:
-      - master
-
-permissions:
-  contents: read
-
-jobs:
-  unittest:
-    # By default, only version is printed out in parens, e.g. "unittest (3.10)"
-    # This changes it to "unittest (python3.10)"
-    name: "unittest (python${{ matrix.python_version }})"
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        python_version: ["3.9", "3.10", "3.11"]
-      fail-fast: false
-    permissions:
-      pull-requests: read  # Used by paths-filter to read the diff.
-    defaults:
-      run:
-        working-directory: 'tools/run_tests/xds_k8s_test_driver'
-
-    steps:
-      - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
-
-      # To add this job to required GitHub checks, it's not enough to use
-      # the on.pull_request.paths filter. For required checks, the job needs to
-      # return the success status, and not be skipped.
-      # Using paths-filter action, we skip the setup/test steps when psm interop
-      # files are unchanged, and the job returns success.
-      - uses: dorny/paths-filter@4512585405083f25c027a35db413c2b3b9006d50 # v2.11.1
-        id: paths_filter
-        with:
-          filters:  |
-            psm_interop_src:
-              - 'tools/run_tests/xds_k8s_test_driver/**'
-              - 'src/proto/grpc/testing/empty.proto'
-              - 'src/proto/grpc/testing/messages.proto'
-              - 'src/proto/grpc/testing/test.proto'
-
-      - uses: actions/setup-python@65d7f2d534ac1bc67fcd62888c5f4f3d2cb2b236 # v4.7.1
-        if: ${{ steps.paths_filter.outputs.psm_interop_src == 'true' }}
-        with:
-          python-version: "${{ matrix.python_version }}"
-          cache: 'pip'
-          cache-dependency-path: 'tools/run_tests/xds_k8s_test_driver/requirements.lock'
-
-      - name: "Install requirements"
-        if: ${{ steps.paths_filter.outputs.psm_interop_src == 'true' }}
-        run: |
-          pip list
-          pip install --upgrade pip setuptools
-          pip list
-          pip install -r requirements.lock
-          pip list
-
-      - name: "Generate protos"
-        if: ${{ steps.paths_filter.outputs.psm_interop_src == 'true' }}
-        run: >
-          python -m grpc_tools.protoc --proto_path=../../../
-          --python_out=. --grpc_python_out=.
-          src/proto/grpc/testing/empty.proto
-          src/proto/grpc/testing/messages.proto
-          src/proto/grpc/testing/test.proto
-
-      - name: "Run unit tests"
-        if: ${{ steps.paths_filter.outputs.psm_interop_src == 'true' }}
-        run: python -m tests.unit