chore: disable default dynamic var snappi fallback (sonic-net#18793)

Description of PR
Summary: Disable the default dynamic variable snappi fallback since T1-tgen testbed does not support this feature yet and currently generating alert. Disabling this now to suspress the alert.

Fixes # (issue) 33123296

Type of change
 Bug fix
 Testbed and Framework(new/improvement)
 New Test case
 Skipped for non-supported platforms
 Test case improvement
Back port request
 202205
 202305
 202311
 202405
 202411
 202505
Approach
What is the motivation for this PR?
Disable the default dynamic variable snappi fallback since T1-tgen testbed does not support this feature yet and currently generating alert. Disabling this now to suspress the alert.

Signed-off-by: Austin Pham <[email protected]>

Author: auspham

tests/conftest.py

@@ -2054,11 +2054,13 @@ def parse_override(testbed, field):
     with open(override_file, 'r') as f:
         all_values = yaml.safe_load(f)
         if testbed not in all_values or field not in all_values[testbed]:
-            return False, None
+            # When T1-tgen is available, we should do "return False, None"
+            return True, []
 
         return True, all_values[testbed][field]
 
-    return False, None
+    # When T1-tgen is available, we should do "return False, None"
+    return True, []
 
 
 def generate_skeleton_port_info(request):