Add workaround to install pip2 on CentOS 7

This installs pip for Python 2 using the get-pip script rather
than the repository package, since the repository pip version
is too old to talk to Pypi to upgrade itself to a newer version.

(related to YDA-5832)

roles/irods_icat/tasks/setup_pam.yml

@@ -44,14 +44,6 @@
   when: external_users
 
 
-- name: Ensure Python dependencies are installed
-  ansible.builtin.package:
-    name:
-      - python-pip
-    state: present
-  when: enable_tokens
-
-
 # When data access tokens are enabled, pysqlcipher3 needs to be
 # installed globally too for the token authentication script
 # (in addition to the user-level installation for the ruleset).

roles/python_irodsclient/tasks/main.yml

@@ -1,17 +1,27 @@
 ---
 # copyright Utrecht University
 
-- name: Ensure Python dependencies are installed
-  ansible.builtin.package:
-    name:
-      - python-pip
-    state: present
+- name: Download get-pip script for Python 2.7
+  ansible.builtin.get_url:
+    url: 'https://bootstrap.pypa.io/pip/2.7/get-pip.py'
+    dest: '/usr/local/bin/get-pip.py'
+    checksum: 'sha256:40ee07eac6674b8d60fce2bbabc148cf0e2f1408c167683f110fd608b8d6f416'
+    mode: '0755'
+
+
+# The packaged pip2 version on CentOS 7 is so ancient that it can't talk
+# to pypi anymore, so we need to use the get-pip script to be able to
+# bootstrap pip for Python 2
+- name: Install pip for Python 2.7
+  become: true
+  ansible.builtin.command:
+    cmd: /usr/bin/python2.7 /usr/local/bin/get-pip.py --prefix /usr
+    creates: /usr/local/bin/pip2
 
 
 - name: Ensure python-irodsclient dependencies are installed
   ansible.builtin.pip:
     name:
-      - pip==20.2.4
       - setuptools==44.1.1
     state: present
 

roles/yoda_rulesets/tasks/main.yml

@@ -5,7 +5,6 @@
 - name: Ensure Python dependencies are installed
   ansible.builtin.package:
     name:
-      - python-pip
       - gcc
     state: present
 

roles/yoda_test_users_eus/tasks/main.yml

@@ -21,12 +21,6 @@
   changed_when: false
 
 
-- name: Ensure Python pip is installed
-  ansible.builtin.package:
-    name: python-pip
-    state: present
-
-
 - name: Install passlib and dependencies
   ansible.builtin.pip:
     name: