[test] move tcplp tests into unit workflow (openthread#8707)

The tcplp test is not testing POSIX platform. This commit creates a new
workflow unit to host this test. In future, we may put all unit tests
in this workflow after automake support is removed.

.github/workflows/posix.yml

@@ -124,22 +124,6 @@ jobs:
       with:
         name: cov-expects-linux-2
         path: tmp/coverage.info
-
-  tcplp-buffering:
-    runs-on: ubuntu-20.04
-    steps:
-    - name: Harden Runner
-      uses: step-security/harden-runner@18bf8ad2ca49c14cbb28b91346d626ccfb00c518 # v2.1.0
-      with:
-        egress-policy: audit # TODO: change to 'egress-policy: block' after couple of runs
-
-    - uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c # v3.3.0
-      with:
-        submodules: true
-    - name: Build
-      run: make -C third_party/tcplp/lib/test/
-    - name: Run
-      run: third_party/tcplp/lib/test/test_all
 
   thread-cert:
     runs-on: ubuntu-20.04

.github/workflows/unit.yml

@@ -0,0 +1,62 @@
+#
+#  Copyright (c) 2023, The OpenThread Authors.
+#  All rights reserved.
+#
+#  Redistribution and use in source and binary forms, with or without
+#  modification, are permitted provided that the following conditions are met:
+#  1. Redistributions of source code must retain the above copyright
+#     notice, this list of conditions and the following disclaimer.
+#  2. Redistributions in binary form must reproduce the above copyright
+#     notice, this list of conditions and the following disclaimer in the
+#     documentation and/or other materials provided with the distribution.
+#  3. Neither the name of the copyright holder nor the
+#     names of its contributors may be used to endorse or promote products
+#     derived from this software without specific prior written permission.
+#
+#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+#  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+#  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+#  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+#  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+#  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+#  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+#  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+#  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+#  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+#  POSSIBILITY OF SUCH DAMAGE.
+#
+
+name: Unit
+
+on:
+  push:
+    branches-ignore:
+      - 'dependabot/**'
+  pull_request:
+    branches:
+      - 'main'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || (github.repository == 'openthread/openthread' && github.run_id) || github.ref }}
+  cancel-in-progress: true
+
+permissions:  # added using https://github.com/step-security/secure-workflows
+  contents: read
+
+jobs:
+
+  tcplp-buffering:
+    runs-on: ubuntu-20.04
+    steps:
+    - name: Harden Runner
+      uses: step-security/harden-runner@18bf8ad2ca49c14cbb28b91346d626ccfb00c518 # v2.1.0
+      with:
+        egress-policy: audit # TODO: change to 'egress-policy: block' after couple of runs
+
+    - uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c # v3.3.0
+      with:
+        submodules: true
+    - name: Build
+      run: make -C third_party/tcplp/lib/test/
+    - name: Run
+      run: third_party/tcplp/lib/test/test_all