Avoid wording about 'lock-in to BTP' (#1382)

The current language of a 'lock-in to SAP BTP' is unfortunate and could
be misunderstood. Make it a bit more neutral.

---------

Co-authored-by: Mahati Shankar <93712176+smahati@users.noreply.github.com>

node.js/authentication.md

@@ -343,10 +343,6 @@ npm add @sap/xssec
 
 [See **XSUAA in Hybrid Setup** below for additional information of how to test this](#xsuaa-setup){.learn-more}
 
-::: warning
-It's recommended to only use this authentication kind if it's necessary for your use case, as it denotes a lock-in to SAP BTP.
-:::
-
 
 ### IAS-based Authentication { #ias }