Minor default template tweaks (#758)

Minor template tweaks, mostly making the imports section for DLT
notebooks a bit more elegant.

Tested with DAB deployment + in-workspace UI.

libs/template/templates/default-python/template/__preamble.tmpl

@@ -17,7 +17,7 @@ This file only template directives; it is skipped for the actual output.
 
 {{if $notPython}}
   {{skip "{{.project_name}}/src/{{.project_name}}"}}
-  {{skip "{{.project_name}}/tests/test_main.py"}}
+  {{skip "{{.project_name}}/tests/main_test.py"}}
   {{skip "{{.project_name}}/setup.py"}}
   {{skip "{{.project_name}}/pytest.ini"}}
 {{end}}

libs/template/templates/default-python/template/{{.project_name}}/README.md.tmpl

@@ -20,7 +20,7 @@ The '{{.project_name}}' project was generated by using the default-python templa
 
     This deploys everything that's defined for this project.
     For example, the default template would deploy a job called
-    `[dev yourname] {{.project_name}}-job` to your workspace.
+    `[dev yourname] {{.project_name}}_job` to your workspace.
     You can find that job by opening your workpace and clicking on **Workflows**.
 
 4. Similarly, to deploy a production copy, type:

libs/template/templates/default-python/template/{{.project_name}}/fixtures/.gitkeep.tmpl

@@ -17,7 +17,7 @@ def get_absolute_path(*relative_parts):
     if 'dbutils' in globals():
         base_dir = os.path.dirname(dbutils.notebook.entry_point.getDbutils().notebook().getContext().notebookPath().get()) # type: ignore
         path = os.path.normpath(os.path.join(base_dir, *relative_parts))
-        return path if path.startswith("/Workspace") else os.path.join("/Workspace", path)
+        return path if path.startswith("/Workspace") else "/Workspace" + path
     else:
         return os.path.join(*relative_parts)
 

libs/template/templates/default-python/template/{{.project_name}}/resources/{{.project_name}}_pipeline.yml.tmpl

@@ -2,11 +2,11 @@
 resources:
   pipelines:
     {{.project_name}}_pipeline:
-      name: "{{.project_name}}_pipeline"
-      target: "{{.project_name}}_${bundle.environment}"
+      name: {{.project_name}}_pipeline
+      target: {{.project_name}}_${bundle.environment}
       libraries:
         - notebook:
             path: ../src/dlt_pipeline.ipynb
 
       configuration:
-        "bundle.sourcePath": "/Workspace/${workspace.file_path}/src"
+        bundle.sourcePath: /Workspace/${workspace.file_path}/src

libs/template/templates/default-python/template/{{.project_name}}/src/dlt_pipeline.ipynb.tmpl

@@ -14,7 +14,7 @@
    "source": [
     "# DLT pipeline\n",
     "\n",
-    "This Delta Live Tables (DLT) definition is executed using a pipeline defined in resources/{{.my_project}}_pipeline.yml."
+    "This Delta Live Tables (DLT) definition is executed using a pipeline defined in resources/{{.project_name}}_pipeline.yml."
    ]
   },
   {
@@ -27,28 +27,18 @@
      "nuid": "9198e987-5606-403d-9f6d-8f14e6a4017f",
      "showTitle": false,
      "title": ""
-    },
-    "jupyter": {
-     {{- /* Collapse this cell by default. Just boring imports here! */}}
-     "source_hidden": true
     }
    },
    "outputs": [],
    "source": [
    {{- if (eq .include_python "yes") }}
-    "# Import DLT and make sure 'my_project' is on the Python path\n",
+    "# Import DLT and src/{{.project_name}}\n",
     "import dlt\n",
-    "from pyspark.sql.functions import expr\n",
-    "from pyspark.sql import SparkSession\n",
-    "spark = SparkSession.builder.getOrCreate()\n",
     "import sys\n",
-    "try:\n",
-    "  sys.path.append(spark.conf.get(\"bundle.sourcePath\"))\n",
-    "except:\n",
-    "  pass\n",
-    "from my_project import main"
+    "sys.path.append(spark.conf.get(\"bundle.sourcePath\", \".\"))\n",
+    "from pyspark.sql.functions import expr\n",
+    "from {{.project_name}} import main"
    {{else}}
-    "# Import DLT\n",
     "import dlt\n",
     "from pyspark.sql.functions import expr\n",
     "from pyspark.sql import SparkSession\n",

libs/template/templates/default-python/template/{{.project_name}}/src/notebook.ipynb.tmpl

@@ -14,7 +14,7 @@
    "source": [
     "# Default notebook\n",
     "\n",
-    "This default notebook is executed using Databricks Workflows as defined in resources/{{.my_project}}_job.yml."
+    "This default notebook is executed using Databricks Workflows as defined in resources/{{.project_name}}_job.yml."
    ]
   },
   {