Backport to Plasma/6.7: Revert "Set NoNewPrivileges on the krdpserver systemd service"
Cherry-picks the master revert 981319d3 (Revert "Set NoNewPrivileges on the krdpserver systemd service", BUG: 521776) onto the Plasma/6.7 stable branch.
The revert landed on master on 2026-06-25 but was never backported, so 6.7.3 (and the pending 6.7.4) still ship NoNewPrivileges=true on the krdpserver unit. That breaks PAM system-password authentication for everyone relying on it: NoNewPrivileges=true stops the setuid-root unix_chkpwd helper (spawned by pam_unix) from reading /etc/shadow, so pamAuthenticate() fails for any password, including the correct one.
Observed on 6.7.3: a client authenticates over TLS with the correct system password, but onPostConnect logs unix_chkpwd: password check failed / pam_authenticate failure (PAM_AUTHINFO_UNAVAIL) and PostConnect fails. Setting NoNewPrivileges=false restores authentication immediately. As noted in the original revert: "The PAM backend needs privs to check."
Straight cherry-pick of the maintainer's own revert, no changes.