cmake/FindLDAP: avoid framework locations for libs too (Apple)

cmake/FindLDAP: avoid framework locations for libs too (Apple)

We already avoid system framework paths while looking for LDAP headers
to avoid issues.

Do the same while looking for LDAP libraries. This makes sure to find
the regular ldap library (`libldap.tbd`) instead of picking up
`ldap.framework` and let that seep into `libcurl.pc` with a full path.

This makes LDAP detection work on Apple as before introducing FindLDAP.

Follow-up to 49f2a23d509645d534cbb2e2ffbd6347fac6e59e #15273
Closes #15895