[FAB-14324] remove CredentialSupport#ClientRootCAs
[FAB-14324] remove CredentialSupport#ClientRootCAs

- field was not used

Change-Id: I90ca92eeb98b01840c11a320cec35425e5a04b4b
Signed-off-by: Matthew Sykes <89c6e4c9c1046731a9c37abefc223a83de36a5d9@us.ibm.com>

muralisrini/fabric,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,binhn/fabric,manish-sethi/fabric-sidedb,stemlending/fabric,hyperledger/fabric,jimthematrix/fabric,jimthematrix/fabric,manish-sethi/fabric,muralisrini/fabric,muralisrini/fabric,stemlending/fabric,hyperledger/fabric,binhn/fabric,stemlending/fabric,stemlending/fabric,manish-sethi/fabric-sidedb,binhn/fabric,manish-sethi/fabric