Incorrect function name in file_handler test

[SohamRatnaparkhi]

What happened:
When we try to run the file_handler test file in rest_handlers (link), the build of this test(test in the link) fails because there is no function named ClusterCreateJWT.

What you expected to happen:
The test should succeed.

Where can this issue be corrected? (optional)

The correct function name should be CreateClusterJWT as seen in file graphql-server/pkg/cluster/cluster_jwt.go

How to reproduce it (as minimally and precisely as possible):
From the root directory, run the command - go test ./litmus-portal/graphql-server/pkg/rest_handlers/file_handler_test.go

[amityt]

The fix will be taken as part of this PR: #4009