Run integration jobs for requirements.txt changes

currently we do not run the gate jobs if any change is for
test|requirements.txt only which can break the things.
Example- https://review.openstack.org/#/c/649804/

Because Tempest does not have functional testing which might
be enough for teting the requirement change, we start running
the all gate jobs for such change.

Change-Id: I54384f5c664673ef32937cd1d7c4a46c10c18f9b
diff --git a/.zuul.yaml b/.zuul.yaml
index 7d77b71..7e3d15b 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -510,7 +510,6 @@
         - tempest-full-parallel:
             # Define list of irrelevant files to use everywhere else
             irrelevant-files: &tempest-irrelevant-files
-              - ^(test-|)requirements.txt$
               - ^.*\.rst$
               - ^doc/.*$
               - ^etc/.*$
@@ -544,7 +543,6 @@
             irrelevant-files: *tempest-irrelevant-files
         - tempest-tox-plugin-sanity-check:
             irrelevant-files:
-              - ^(test-|)requirements.txt$
               - ^.*\.rst$
               - ^doc/.*$
               - ^etc/.*$