[MM-57085] Remove UseNewSAMLLibrary experimental setting (#26392)

Co-authored-by: Mattermost Build <build@mattermost.com>

e2e-tests/playwright/support/server/default_config.ts

@@ -573,7 +573,6 @@ const defaultServerConfig: AdminConfig = {
         ClientSideCertCheck: 'secondary',
         LinkMetadataTimeoutMilliseconds: 5000,
         RestrictSystemAdmin: false,
-        UseNewSAMLLibrary: false,
         EnableSharedChannels: false,
         EnableRemoteClusterService: false,
         DisableAppBar: false,