e2e-rt simple-keyvalue flaking on CI

[pro-wh]

{"caller":"simplekvtest.go:259","level":"info","module":"scenario/e2e/test-runtime-simple-keyvalue","msg":"create new key in the keymanager","ts":"2021-10-04T22:37:09.659726778Z"} {"caller":"simplekvtest.go:265","level":"info","module":"scenario/e2e/test-runtime-simple-keyvalue","msg":"test 'confidential' insert","ts":"2021-10-04T22:37:12.252390753Z"} {"caller":"runtime.go:367","err":"failed to submit transaction: module: core code: 18 message: invalid call format: Tag verification failed","level":"error","module":"scenario/e2e/test-runtime-simple-keyvalue","msg":"test failed","test":"main.ConfidentialTest","ts":"2021-10-04T22:37:16.635435071Z"}

observed this on main after it passed in a PR's run