[action] [PR:21582] fix: only disable route check for T2 (#930)

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### Description of PR
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- Please include a summary of the change and which issue is fixed.
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Change the `temporarily_disable_route_check` fixture logic to only apply
to T2 topology for now.

Summary:
Fixes # (issue) Microsoft ADO 36101536

### Type of change

<!--
- Fill x for your type of change.
- e.g.
- [x] Bug fix
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- [x] 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
- [x] 202505
- [x] 202511

### Approach
#### What is the motivation for this PR?
The current disable-and-enable routeCheck monitor logic is causing test
flakiness on some non-T2 platforms (see
sonic-net/sonic-mgmt#16876 (comment)).
Certain platforms require additional time to restart the routeCheck
monitor, which can leave it inactive when the next test begins and
result in false failures. We would like to address this issue urgently
in this PR.

In a follow-up PR, I will properly enhance the
`temporarily_disable_route_check` fixture so that:
- Users can choose which topologies apply the disable-and-enable
routeCheck behavior
- The fixture uses a `wait_until()` timeout to verify the routeCheck
status is as expected before proceeding to the next step

#### How did you do it?

#### How did you verify/test it?
I ran the updated login on a non-T2 platform (Mx) and can confirm it's
working well:
https://elastictest.org/scheduler/testplan/693272f7392767e9bf67e930
<img width="1609" height="202" alt="image"
src="https://github.com/user-attachments/assets/e631a351-1372-412d-bca7-6b4ef5d8112a"
/>

I also verified the logic on T2 platform and can confirm it's still
having this logic:
https://elastictest.org/scheduler/testplan/6932767fbcc3fac23371a83c
<img width="1963" height="546" alt="image"
src="https://github.com/user-attachments/assets/261dd79b-c847-4a82-9409-d87e48a3cfa8"
/>

#### Any platform specific information?

#### Supported testbed topology if it's a new test case?

### Documentation
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(If it's a new feature, new test case)
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Link to the wiki page?
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Author: mssonicbld

tests/conftest.py

@@ -2733,13 +2733,17 @@ def _remove_entry(table_name, key_name, config):
 
 
 @pytest.fixture(scope="module", autouse=True)
-def temporarily_disable_route_check(request, duthosts):
+def temporarily_disable_route_check(request, tbinfo, duthosts):
     check_flag = False
     for m in request.node.iter_markers():
         if m.name == "disable_route_check":
             check_flag = True
             break
 
+    if 't2' not in tbinfo['topo']['name']:
+        logger.info("Topology is not T2, skipping temporarily_disable_route_check fixture")
+        check_flag = False
+
     def wait_for_route_check_to_pass(dut):
 
         def run_route_check():

tests/pc/test_po_cleanup.py

@@ -40,10 +40,13 @@ def ignore_expected_loganalyzer_exceptions(enum_rand_one_per_hwsku_frontend_host
 
 
 @pytest.fixture(autouse=True)
-def disable_route_check_for_duthost(duthosts, enum_rand_one_per_hwsku_frontend_hostname):
-    duthost = duthosts[enum_rand_one_per_hwsku_frontend_hostname]
-    logging.info("Stopping route check on DUT {}".format(duthost.hostname))
-    stop_route_checker_on_duthost(duthost)
+def disable_route_check_for_duthost(tbinfo, duthosts, enum_rand_one_per_hwsku_frontend_hostname):
+    if 't2' not in tbinfo['topo']['name']:
+        logging.info("Topology is not T2, skipping disabling route check")
+    else:
+        duthost = duthosts[enum_rand_one_per_hwsku_frontend_hostname]
+        logging.info("Stopping route check on DUT {}".format(duthost.hostname))
+        stop_route_checker_on_duthost(duthost)
 
     yield