Improve the performance when using enumeration

[aplopez]

This PR includes:

• Removal of an unused function.
• Stop logging a possibly extremely long filter.
• Fixes a wrong condition invalidating an optimization.
• Adds a test case for an existing test.

Enumeration, specially when there are 15,000+ users, is slow. This fix helps, but it doesn't work miracles.
In my test environment, the enumeration went from 8 minutes to about 1.

It is important to know that, with such an amount of users, many operations time out. It is necessary to increment the timeout in[nss] and for the domain, but also set large values for ldap_enumeration_refresh_timeout and ldap_search_timeout in the domain. I used these values to avoid any timeout (YMMV):

[domain/ldap.test]
ldap_enumeration_refresh_timeout = 30000
ldap_search_timeout = 6000
timeout = 6000
...

[nss]
timeout = 6000
...

[gemini-code-assist]

Code Review

This pull request effectively improves performance by optimizing logging, removing an unused function, and correcting a condition related to enumeration. The changes are well-aligned with the stated goals of enhancing enumeration performance, especially for large user bases. The addition of a new test case for the general enumeration scenario ensures that the modified logic is adequately covered.

[alexey-tikhonov]

Mistype in the commit message: "We must look into de TS cache"

[aplopez]

Mistype in the commit message: "We must look into de TS cache"

Fixed.

[alexey-tikhonov]

I think fix is correct in the sense it fixes a bug.

But I think logic of sysdb_enumpwent_filter() can and should be improved in general to avoid a case when dn_filter expands to entire db.

In particular, if addtl_filter isn't set, then sysdb_search_ts_users(enum_filter(NULL)) is expected to return entire db, right? And using this as additional filter results in the same as '*' but extremely slow.
Or do I miss something?