Add Helm repository fail on VelaUX

[StevenLeiZhang]

reproduce :

1. enable addon fluxCD
2. go to velaux
3. goto "integrations"
4. click "Helm Repository"
5. click button "Add"
6. fill textbox Url, Username and Password
7. click button "save"
8. velaux returns error
   9.api-server raises these errors

{"level":"error","ts":1652687180.283481,"caller":"bcode/bcode.go:102","msg":"Business exceptions, error message: admission webhook "validating.core.oam.dev.v1beta1.applications" denied the request: field "schematic": Invalid value error encountered, cannot create the validation process context of app=eeee in namespace=vela-system: evaluate base template app=eeee in namespace=vela-system: invalid cue template of workload eeee after merge parameter and context: output.stringData.username: conflicting values "xxxxxxxx" and "yyyyyy". , path:/api/v1/config_types/config-helm-repository method:POST","stacktrace":"github.com/oam-dev/kubevela/pkg/apiserver/rest/utils/bcode.ReturnError\n\t/workspace/pkg/apiserver/rest/utils/bcode/bcode.go:102\ngithub.com/oam-dev/kubevela/pkg/apiserver/rest/webservice.(*configWebService).createConfig\n\t/workspace/pkg/apiserver/rest/webservice/config.go:153\ngithub.com/emicklei/go-restful/v3.(*FilterChain).ProcessFilter\n\t/go/pkg/mod/github.com/emicklei/go-restful/v3@v3.0.0-rc2/filter.go:21\ngithub.com/oam-dev/kubevela/pkg/apiserver/rest/usecase.(*rbacUsecaseImpl).CheckPerm.func1\n\t/workspace/pkg/apiserver/rest/usecase/rbac.go:554\ngithub.com/emicklei/go-restful/v3.(*FilterChain).ProcessFilter\n\t/go/pkg/mod/github.com/emicklei/go-restful/v3@v3.0.0-rc2/filter.go:19\ngithub.com/oam-dev/kubevela/pkg/apiserver/rest/webservice.authCheckFilter\n\t/workspace/pkg/apiserver/rest/webservice/authentication.go:115\ngithub.com/emicklei/go-restful/v3.(*FilterChain).ProcessFilter\n\t/go/pkg/mod/github.com/emicklei/go-restful/v3@v3.0.0-rc2/filter.go:19\ngithub.com/oam-dev/kubevela/pkg/apiserver/rest.(*restServer).requestLog\n\t/workspace/pkg/apiserver/rest/rest_server.go:230\ngithub.com/emicklei/go-restful/v3.(*FilterChain).ProcessFilter\n\t/go/pkg/mod/github.com/emicklei/go-restful/v3@v3.0.0-rc2/filter.go:19\ngithub.com/emicklei/go-restful/v3.(*Container).OPTIONSFilter\n\t/go/pkg/mod/github.com/emicklei/go-restful/v3@v3.0.0-rc2/options_filter.go:15\ngithub.com/emicklei/go-restful/v3.(*FilterChain).ProcessFilter\n\t/go/pkg/mod/github.com/emicklei/go-restful/v3@v3.0.0-rc2/filter.go:19\ngithub.com/emicklei/go-restful/v3.CrossOriginResourceSharing.Filter\n\t/go/pkg/mod/github.com/emicklei/go-restful/v3@v3.0.0-rc2/cors_filter.go:52\ngithub.com/emicklei/go-restful/v3.(*FilterChain).ProcessFilter\n\t/go/pkg/mod/github.com/emicklei/go-restful/v3@v3.0.0-rc2/filter.go:19\ngithub.com/emicklei/go-restful/v3.(*Container).dispatch\n\t/go/pkg/mod/github.com/emicklei/go-restful/v3@v3.0.0-rc2/container.go:282\nnet/http.HandlerFunc.ServeHTTP\n\t/usr/local/go/src/net/http/server.go:2047\nnet/http.(*ServeMux).ServeHTTP\n\t/usr/local/go/src/net/http/server.go:2425\ngithub.com/emicklei/go-restful/v3.(*Container).ServeHTTP\n\t/go/pkg/mod/github.com/emicklei/go-restful/v3@v3.0.0-rc2/container.go:300\nnet/http.serverHandler.ServeHTTP\n\t/usr/local/go/src/net/http/server.go:2879\nnet/http.(*conn).serve\n\t/usr/local/go/src/net/http/server.go:1930"}
{"level":"info","ts":1652687180.2836726,"caller":"rest/rest_server.go:239","msg":"request log","clientIP":"10.1.7.112","path":"/api/v1/config_types/config-helm-repository","method":"POST","status":500,"time":"25.704548ms","responseSize":481}