refactor!: Pass LDAP mapping request bodies by value via new UpdateUserLDAPMappingRequest and UpdateTeamLDAPMappingRequest

[JamBalaya56562]

Continues the request-body-by-value work in #3644, this time for the two LDAP mapping endpoints on AdminService.

Both methods reused their response types as request bodies, but per the GHES docs each endpoint accepts exactly one body parameter, ldap_dn, and it's required:

• UpdateUserLDAPMapping took *UserLDAPMapping — 17 all-pointer fields, most of them server-generated (avatar_url, events_url, …).
• UpdateTeamLDAPMapping took *TeamLDAPMapping — 10 all-pointer fields, same story.

The existing tests show this: both build the request with only LDAPDN set, while the response expectations populate more fields. So this adds dedicated request types, following the same approach as PullRequestSubmitReviewRequest (#4406) and UpdateConnectedExternalGroupRequest (#4425):

typeUpdateUserLDAPMappingRequeststruct {
LDAPDNstring`json:"ldap_dn"`
}
typeUpdateTeamLDAPMappingRequeststruct {
LDAPDNstring`json:"ldap_dn"`
}

LDAPDN is a non-pointer string since it's required, both bodies are passed by value, and both old entries are removed from the body-allowed-pointer-types allowlist. The two methods live in the same file and follow the identical pattern, so they're converted together.

Notes:

• UserLDAPMapping and TeamLDAPMapping are unchanged — they stay the response types, so their fields keep pointer semantics.
• The method verbs already match the docs operation names ("Update LDAP mapping for a user/team"), so no method rename.
• The team int64 parameter is renamed to teamID for clarity (non-breaking).

Verified with go build ./..., go vet -tags integration ./test/integration/, gofmt, the full ./github/ test suite (both methods and the generated GetLDAPDN accessors at 100%), and custom-gcl (no paramcheck findings after removing the allowlist entries).

Updates #3644

BREAKING CHANGE: AdminService.UpdateUserLDAPMapping and UpdateTeamLDAPMapping now take new UpdateUserLDAPMappingRequest and UpdateTeamLDAPMappingRequest (with non-pointer LDAPDN) by value instead of *UserLDAPMapping and *TeamLDAPMapping.

cc @jvm986 — flagging for #3644 coordination; this is in the admin service, so it shouldn't overlap with the Issues work.

[jvm986]

Looks good to me!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.54%. Comparing base (40d29ba) to head (07656f5).

Additional details and impacted files

@@ Coverage Diff @@## master #4432 +/- ##
=======================================
Coverage 97.54% 97.54% =======================================
Files 194 194 Lines 19836 19836 =======================================
Hits 19350 19350 Misses 268 268 Partials 218 218 

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[gmlewis]

Thank you, @JamBalaya56562 and @jvm986!
LGTM.
Merging.