Add unique ID to `root_path` for bundle integration test fixtures (#1917)

## Changes
Integration tests using these fixtures could have been flaky when run in
parallel using the same user's identity. They would also possibly have
piggybacked state from previous runs.

This PR adds a UUID to the root_path to force independent bundle
deployments for every test run.

I have checked that all bundles in `internal/bundle/bundles` have
`root_path` namespaced to a UUID.

## Tests
Self testing.

internal/bundle/bundles/empty_bundle/databricks.yml

@@ -1,2 +0,0 @@
-bundle:
-  name: abc

internal/bundle/bundles/recreate_pipeline/template/databricks.yml.tmpl

@@ -1,5 +1,8 @@
 bundle:
-  name: "bundle-playground"
+  name: recreate-pipeline
+
+workspace:
+  root_path: "~/.bundle/{{.unique_id}}"
 
 variables:
   catalog:

internal/bundle/bundles/uc_schema/template/databricks.yml.tmpl

@@ -1,5 +1,8 @@
 bundle:
-  name: "bundle-playground"
+  name: uc-schema
+
+workspace:
+  root_path: "~/.bundle/{{.unique_id}}"
 
 resources:
   pipelines: