[crypto] Remove CI check against mbedTLS 2.x

Signed-off-by: Łukasz Duda <lukasz.duda@nordicsemi.no>

Author: LuDuda

.github/workflows/build.yml

@@ -209,33 +209,6 @@ jobs:
       run: |
         ./script/test build
 
-  mbedtls2-build:
-    runs-on: ubuntu-24.04
-    env:
-      CFLAGS: -DCOPENTHREAD_CONFIG_CRYPTO_LIB=OPENTHREAD_CONFIG_CRYPTO_LIB_MBEDTLS -DOPENTHREAD_CONFIG_PLATFORM_KEY_REFERENCES_ENABLE=0
-      CXXFLAGS: -DCOPENTHREAD_CONFIG_CRYPTO_LIB=OPENTHREAD_CONFIG_CRYPTO_LIB_MBEDTLS -DOPENTHREAD_CONFIG_PLATFORM_KEY_REFERENCES_ENABLE=0
-    steps:
-    - name: Harden Runner
-      uses: step-security/harden-runner@0080882f6c36860b6ba35c610c98ce87d4e2f26f # v2.10.2
-      with:
-        egress-policy: audit # TODO: change to 'egress-policy: block' after couple of runs
-
-    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
-      with:
-        submodules: true
-    - name: Bootstrap
-      run: |
-        sudo apt-get --no-install-recommends install -y ninja-build libreadline-dev libncurses-dev
-        rm -rf third_party/mbedtls/repo
-    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
-      with:
-        repository: ARMmbed/mbedtls
-        ref: v2.28.8
-        path: third_party/mbedtls/repo
-    - name: Build
-      run: |
-        ./script/test build
-
   arm-gcc:
     name: arm-gcc-${{ matrix.gcc_ver }}
     runs-on: ubuntu-24.04