Revert "test: dynamically generate list of test cases"

We want to decouple the integration tests in meson from the
rest of the source files so the integration tests can be run
without the source files available. Let's revert the change to
dynamically figure out the test cases from the networkd tests for
now so that the tests can be generated without the test source file
being available.

This reverts commit 514458604b.

test/TEST-85-NETWORK/meson.build

@@ -9,14 +9,27 @@ unit = configure_file(
         },
 )
 
-systemd_networkd_tests_py = files('../test-network/systemd-networkd-tests.py')
-network_testcases = run_command('sed',
-                                '-ne',
-                                '/^class .*Tests/ { s/^class *//; s/(.*$//; p}',
-                                systemd_networkd_tests_py,
-                                check : true).stdout().split()
-
-foreach testcase : network_testcases
+foreach testcase : [
+        'NetworkctlTests',
+        'NetworkdMatchTests',
+        'WaitOnlineTests',
+        'NetworkdNetDevTests',
+        'NetworkdL2TPTests',
+        'NetworkdNetworkTests',
+        'NetworkdTCTests',
+        'NetworkdStateFileTests',
+        'NetworkdBondTests',
+        'NetworkdBridgeTests',
+        'NetworkdSRIOVTests',
+        'NetworkdLLDPTests',
+        'NetworkdRATests',
+        'NetworkdDHCPServerTests',
+        'NetworkdDHCPServerRelayAgentTests',
+        'NetworkdDHCPClientTests',
+        'NetworkdDHCPPDTests',
+        'NetworkdIPv6PrefixTests',
+        'NetworkdMTUTests',
+]
         integration_tests += [
                 integration_test_template + {
                         'name' : '@0@-@1@'.format(name, testcase),