GHA/non-native: drop AmigaOS jobs, toolchain no longer available

Fixing:
```
[...] https://github.com/bebbo/amiga-gcc/releases/download/Mechen/amiga-gcc.tgz
curl: (22) The requested URL returned error: 404
```
Ref: https://github.com/curl/curl/actions/runs/15342088546/job/43170188027#step:2:17

Reason:
"As a sign of protest against the refusal to restore 2FA accounts,
this account is now empty."
Ref: https://github.com/bebbo/

If someone happens to have a local copy of the toolchain, we may use it
to restore the AmigaOS jobs.

Closes #17486

.github/workflows/non-native.yml

@@ -485,105 +485,6 @@ jobs:
             make -C bld examples
           fi
 
-  amiga:
-    name: "AmigaOS, ${{ matrix.build == 'cmake' && 'CM' || 'AM' }} gcc AmiSSL m68k"
-    runs-on: 'ubuntu-latest'
-    timeout-minutes: 5
-    env:
-      MAKEFLAGS: -j 5
-      amissl-version: 5.18
-    strategy:
-      matrix:
-        build: [autotools, cmake]
-      fail-fast: false
-    steps:
-      - name: 'install compiler'
-        if: ${{ steps.cache-compiler.outputs.cache-hit != 'true' }}
-        run: |
-          cd "${HOME}" || exit 1
-          curl --disable --fail --silent --show-error --connect-timeout 15 --max-time 120 --retry 3 \
-            --location https://github.com/bebbo/amiga-gcc/releases/download/Mechen/amiga-gcc.tgz | tar -xz
-          cd opt/appveyor || exit 1
-          curl --disable --fail --silent --show-error --connect-timeout 15 --max-time 60 --retry 3 \
-            --location https://github.com/jens-maus/amissl/releases/download/${{ env.amissl-version }}/AmiSSL-${{ env.amissl-version }}-SDK.lha --output bin.lha
-          7z x -bd -y bin.lha
-          rm -f bin.lha
-          mv "$HOME/opt/appveyor" /opt
-
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
-        with:
-          persist-credentials: false
-
-      - name: 'configure'
-        run: |
-          if [ '${{ matrix.build }}' = 'cmake' ]; then
-            cmake -B bld -G Ninja \
-              -DAMIGA=1 \
-              -DCMAKE_SYSTEM_NAME=Generic \
-              -DCMAKE_SYSTEM_PROCESSOR=m68k \
-              -DCMAKE_C_COMPILER_TARGET=m68k-unknown-amigaos \
-              -DCMAKE_C_COMPILER=/opt/appveyor/build-agent/opt/amiga/bin/m68k-amigaos-gcc \
-              -DCMAKE_C_FLAGS='-O0 -msoft-float -mcrt=clib2' \
-              -DCMAKE_UNITY_BUILD=ON -DCURL_TEST_BUNDLES=ON \
-              -DCURL_WERROR=ON \
-              -DCURL_USE_LIBPSL=OFF \
-              -DAMISSL_INCLUDE_DIR=/opt/appveyor/AmiSSL/Developer/include \
-              -DAMISSL_STUBS_LIBRARY=/opt/appveyor/AmiSSL/Developer/lib/AmigaOS3/libamisslstubs.a \
-              -DAMISSL_AUTO_LIBRARY=/opt/appveyor/AmiSSL/Developer/lib/AmigaOS3/libamisslauto.a
-          else
-            autoreconf -fi
-            mkdir bld && cd bld && ../configure --disable-dependency-tracking --enable-unity --enable-test-bundles --enable-warnings --enable-werror \
-              CC=/opt/appveyor/build-agent/opt/amiga/bin/m68k-amigaos-gcc \
-              AR=/opt/appveyor/build-agent/opt/amiga/bin/m68k-amigaos-ar \
-              RANLIB=/opt/appveyor/build-agent/opt/amiga/bin/m68k-amigaos-ranlib \
-              --host=m68k-amigaos \
-              --disable-shared \
-              --without-libpsl \
-              --with-amissl \
-              LDFLAGS=-L/opt/appveyor/AmiSSL/Developer/lib/AmigaOS3 \
-              CPPFLAGS=-I/opt/appveyor/AmiSSL/Developer/include \
-              CFLAGS='-O0 -msoft-float -mcrt=clib2' \
-              LIBS='-lnet -lm -latomic'
-          fi
-
-      - name: 'configure log'
-        if: ${{ !cancelled() }}
-        run: cat bld/config.log bld/CMakeFiles/CMake*.yaml 2>/dev/null || true
-
-      - name: 'curl_config.h'
-        run: |
-          echo '::group::raw'; cat bld/lib/curl_config.h || true; echo '::endgroup::'
-          grep -F '#define' bld/lib/curl_config.h | sort || true
-
-      - name: 'build'
-        run: |
-          if [ '${{ matrix.build }}' = 'cmake' ]; then
-            cmake --build bld
-          else
-            make -C bld
-          fi
-
-      - name: 'curl info'
-        run: find . -type f \( -name curl -o -name '*.a' \) -exec file '{}' \;
-
-      - name: 'build tests'
-        if: ${{ matrix.build == 'cmake' }}  # skip for autotools to save time
-        run: |
-          if [ '${{ matrix.build }}' = 'cmake' ]; then
-            cmake --build bld --target testdeps
-          else
-            make -C bld -C tests
-          fi
-
-      - name: 'build examples'
-        if: ${{ matrix.build == 'cmake' }}  # skip for autotools to save time
-        run: |
-          if [ '${{ matrix.build }}' = 'cmake' ]; then
-            cmake --build bld --target curl-examples
-          else
-            make -C bld examples
-          fi
-
   msdos:
     name: "MS-DOS, ${{ matrix.build == 'cmake' && 'CM' || 'AM' }} djgpp openssl i586"
     runs-on: 'ubuntu-latest'