scons: Remove the plumbing for running regression tests from scons.

All of these tests have been migrated to the new framework, so there's
no reason to leave the old plumbing lying around.

Change-Id: Iaa5412864354d5754a68a9f53f30aa42f07ec2eb
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/32117
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>

src/SConscript

@@ -1315,11 +1315,6 @@ def makeEnv(env, label, objsfx, strip=False, **kwargs):
     new_env.Command(secondary_exename, new_env.M5Binary,
             MakeAction('ln $SOURCE $TARGET', Transform("HARDLINK")))
 
-    # Set up regression tests.
-    SConscript(os.path.join(env.root.abspath, 'tests', 'SConscript'),
-               variant_dir=Dir('tests').Dir(new_env.Label),
-               exports={ 'env' : new_env }, duplicate=False)
-
 # Start out with the compiler flags common to all compilers,
 # i.e. they all use -g for opt and -g -pg for prof
 ccflags = {'debug' : [], 'opt' : ['-g'], 'fast' : [], 'prof' : ['-g', '-pg'],
@@ -1374,9 +1369,6 @@ def identifyTarget(t):
         return ext
     if ext in obj2target:
         return obj2target[ext]
-    match = re.search(r'/tests/([^/]+)/', t)
-    if match and match.group(1) in target_types:
-        return match.group(1)
     return 'all'
 
 needed_envs = [identifyTarget(target) for target in BUILD_TARGETS]