test(appsec): run the flask app suites when app.py changes DD_U55XLN

tests/appsec/app.py matched only the threats suites, none of which run the
integration tests that actually serve it, so the shutdown change in the previous
commit shipped without any of them running. Same gap that #19674 closed for
appsec_utils.py. 15 -> 19 matched suites.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: christophe-papazian

tests/appsec/suitespec.yml

@@ -74,6 +74,7 @@ suites:
     paths:
       - '@appsec_iast'
       - tests/appsec/iast_packages/*
+      - tests/appsec/app.py
       - tests/appsec/appsec_utils.py
     timeout: 50m
   iast_tdd_propagation:
@@ -85,6 +86,7 @@ suites:
       - '@appsec_iast'
       - '@remoteconfig'
       - tests/appsec/iast_tdd_propagation/*
+      - tests/appsec/app.py
       - tests/appsec/appsec_utils.py
     retry: 2
     snapshot: true
@@ -150,6 +152,7 @@ suites:
       - '@appsec_iast'
       - tests/appsec/integrations/flask_tests/test_iast_flask.py
       - tests/appsec/integrations/flask_tests/test_appsec_flask_telemetry.py
+      - tests/appsec/app.py
       - tests/appsec/appsec_utils.py
     retry: 2
     # test_appsec_flask_telemetry.py asserts on payloads received by the test agent.
@@ -165,6 +168,7 @@ suites:
       - '@appsec_iast'
       - '@remoteconfig'
       - tests/appsec/integrations/flask_tests/*
+      - tests/appsec/app.py
       - tests/appsec/appsec_utils.py
     retry: 2
     services: