remove cache from big pages

[simonLeary42]

Fixes the slowness issues that created the need for redis cache. user-mgmt and pi-mgmt should no longer be relying on redis at all. UnityUser->getGroups still uses cache by default, but it should enable us to remove cache later.

• UnityUser->getGroups() -> UnityUser->getPIGroupGIDs():
  • before:
    • query LDAP for all PI groups (all attributes)
    • initialize an object for each PI group
    • filter for PI groups with membership
  • after:
    • query LDAP for PI groups with this user as a member
• pi-mgmt.php:
  • before (without cache):
    • query LDAP for all PI groups (all attributes)
    • initialize a UnityUser object for each PI group owner
    • query LDAP separately for name, UID, and email for each PI group owner
  • after:
    • query LDAP for all PI groups (GIDs only)
    • query LDAP for all users (gecos, UID, and mail only)
• user-mgmt.php:
  • before (without cache):
    • query LDAP for all users (all attributes)
    • initialize a UnityUser object for each user
    • query LDAP separately for name, org, UID, and email for each user
  • after:
    • query LDAP for all users (name, org, UID, and email only)