fix: Set HELM_HOME to /tekton/home/.helm

`/builder/home` is now `/tekton/home` since we've upgraded to Tekton
0.11.3, so the old path is breaking release builds.

Signed-off-by: Andrew Bayer <andrew.bayer@gmail.com>

jenkins-x.yml

@@ -24,7 +24,7 @@ pipelineConfig:
               - name: BASE_WORKSPACE
                 value: /workspace/source
               - name: HELM_HOME
-                value: /builder/home/.helm
+                value: /tekton/home/.helm
               - name: GOPATH
                 value: /workspace/go
               - name: GOPROXY