ci: build musl only for arm64 and reuse toolchain cache [CI]

scripts/test-linux-agent-build.py

@@ -80,7 +80,7 @@ esac
                        OLD_TIME=str(int(time.time()) - 8 * 86400), RECENT_TIME=str(int(time.time())),
                        CONTAINERS_STORAGE_CONF=str(base / 'moshiro-storage.conf'))
             subprocess.run(['bash', str(ROOT / 'ci/cleanup-build-cache.sh')], env=env, check=True, capture_output=True)
-            self.assertEqual((base / 'removed').read_text(), 'rmi old\nrmi version\n')
+            self.assertEqual((base / 'removed').read_text(), 'rmi localhost/moshiro-agent-binaries:linux-musl-x64\nrmi old\nrmi version\n')
 
     def test_export_requires_one_unshare_session_and_cleans_up_on_copy_failure(self):
         with tempfile.TemporaryDirectory() as directory:
@@ -122,7 +122,7 @@ esac
                         self.assertEqual((base / 'output/moshiro-agent').read_bytes(), b'agent')
                         self.assertEqual((base / 'output/fleet-enroll').read_bytes(), b'enroll')
 
-    def test_four_linux_packages_preserve_installers_and_shared_library_payloads(self):
+    def test_linux_packages_preserve_installers_and_shared_library_payloads(self):
         with tempfile.TemporaryDirectory() as directory:
             base = Path(directory)
             binaries = base / 'binaries'
@@ -130,7 +130,7 @@ esac
             for name in ('moshiro-agent', 'fleet-enroll', 'libmsquic.so.2'):
                 (binaries / name).write_bytes(name.encode())
             for rid, suffix in [('linux-x64', 'amd64'), ('linux-arm64', 'arm64'),
-                                ('linux-musl-x64', 'musl-amd64'), ('linux-musl-arm64', 'musl-arm64')]:
+                                ('linux-musl-arm64', 'musl-arm64')]:
                 with self.subTest(rid=rid):
                     output = base / rid
                     env = dict(os.environ, CI_COMMIT_TAG='v1.2.3')