ci: Add a testpack.tar target to tranfer artifacts between CI jobs

The tester CI job uses absolute paths to ensure it is testing the
correct binaries. That clashes with the transfer between builder and
tester job using the `install` target because that switches things
around. This commit introduces a new target that just collects
artifacts in place, and tars them. Then we can use `tar` to unpack
them on the tester jobs again.

.github/workflows/ci.yaml

@@ -105,18 +105,14 @@ jobs:
           python3 -m pip install -r requirements.txt
           ./configure CC="$COMPILER"
 
-          # We'll need lowdown, not present on ubuntu:20.04 yet
-          make -j $(nproc) doc-all  # Builds lowdown as a dependency
-          make -j $(nproc) DESTDIR=${GITHUB_WORKSPACE}/cln-${{ matrix.CFG }} install
+          make -j $(nproc) testpack.tar.bz2
 
-          # The above leaves the binaries installed in
-          # cln-${matrix.CFG}, let's package it up and store it.
-
-          tar -cvzf /tmp/cln-${CFG}.tar.gz cln-${CFG}
+          # Rename now so we don't clash
+          mv testpack.tar cln-${CFG}.tar
       - uses: actions/upload-artifact@v3
         with:
-          name: cln-${{ matrix.CFG }}.tar.gz
-          path: /tmp/cln-${{ matrix.CFG }}.tar.gz
+          name: cln-${{ matrix.CFG }}.tar
+          path: cln-${{ matrix.CFG }}.tar
 
   integration:
     name: Test CLN ${{ matrix.cfg }}
@@ -172,7 +168,7 @@ jobs:
       - name: Download build
         uses: actions/download-artifact@v3
         with:
-          name: cln-${{ matrix.CFG }}.tar.gz
+          name: cln-${{ matrix.CFG }}.tar
 
       - name: Test
         env:
@@ -186,14 +182,10 @@ jobs:
           PYTEST_PAR: 10
         run: |
           set -e
+          tar -xvf cln-${CFG}.tar
+
           pip3 install --user pip wheel poetry
           poetry export -o requirements.txt --with dev --without-hashes
           python3 -m pip install -r requirements.txt
 
-          # Needed in order to run `make` below.
-          ./configure CC="$COMPILER"
-
-          # Only run the `pytest` tests since these are the ones that
-          # really take time, and unit tests should be run in the
-          # `compile` step.
-          make pytest
+          poetry run make pytest