test: Add continuous testing for run-test --jvm

Add testrunner.py --jvm flag which runs run-test --jvm.

The default is still only --host, --target, but if --jvm is specified
by itself then only jvm tests will run.

Also change art-test-javac continuous test target to run with --jvm.

This is a pre-requisite to swapping our non-jvm test targets to build
with libcore instead of openjdk.

Bug: 72491947
Bug: 73888836
Test: art/test/testrunner/testrunner.py -b --jvm
Test: art/test/testrunner/testrunner.py -b --host
Test: art/test/testrunner/run_build_test_target.py art-test-javac
Change-Id: I114327008d57e88409d36ac6713b809e593f7802
diff --git a/test/testrunner/run_build_test_target.py b/test/testrunner/run_build_test_target.py
index 531508e..fcc5505 100755
--- a/test/testrunner/run_build_test_target.py
+++ b/test/testrunner/run_build_test_target.py
@@ -96,15 +96,20 @@
 if target.has_key('run-test'):
   run_test_command = [os.path.join(env.ANDROID_BUILD_TOP,
                                    'art/test/testrunner/testrunner.py')]
-  run_test_command += target.get('run-test', [])
+  test_flags = target.get('run-test', [])
+  run_test_command += test_flags
   # Let testrunner compute concurrency based on #cpus.
   # b/65822340
   # run_test_command += ['-j', str(n_threads)]
+
+  # In the config assume everything will run with --host and on ART.
+  # However for only [--jvm] this is undesirable, so don't pass in ART-specific flags.
+  if ['--jvm'] != test_flags:
+    run_test_command += ['--host']
+    run_test_command += ['--dex2oat-jobs']
+    run_test_command += ['4']
   run_test_command += ['-b']
-  run_test_command += ['--host']
   run_test_command += ['--verbose']
-  run_test_command += ['--dex2oat-jobs']
-  run_test_command += ['4']
 
   sys.stdout.write(str(run_test_command) + '\n')
   sys.stdout.flush()