test: replace localhost IP with 'localhost' for TLS conformity

test-https-connect-localport currently causes a runtime deprecation
warning: "[DEP0123] DeprecationWarning: Setting the TLS ServerName
to an IP address is not permitted by RFC 6066. This will be ignored
in a future version."

Change IP usage to the string 'localhost' instead.

PR-URL: https://github.com/nodejs/node/pull/26881
Fixes: https://github.com/https://github.com/nodejs/node/issues/26862


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>