…rce when it ends with `/`

Right now if we have directory declared as follows:

```hcl
resource "databricks_directory" "test" {
  path = "/Users/user@domain/TF_DIR_WITH_SLASH/"
}
```

on update it's trying to recreate resource because REST API returns normalized path,
without ending `/`, and this leads to following:

```
  # databricks_directory.test must be replaced
-/+ resource "databricks_directory" "test" {
      ~ id               = "/Users/user@domain/TF_DIR_WITH_SLASH/" -> (known after apply)
      ~ object_id        = 696671922817959 -> (known after apply)
      ~ path             = "/Users/user@domain/TF_DIR_WITH_SLASH" -> "/Users/user@domain/TF_DIR_WITH_SLASH/" # forces replacement
        # (1 unchanged attribute hidden)
    }
```

this patch fixes this behavior