feat: update environment configuration and remove deprecated model serving

- Modified `.env.example` to set local defaults for PostgreSQL, MLflow, and MinIO configurations.
- Added MongoDB configuration parameters to the environment setup.
- Updated `README.md` to reflect changes in workflow input parameters and task queue naming conventions.
- Removed the `ModelServing` class to streamline the codebase, as it was deemed unnecessary.
- Adjusted `connectors_config.py` to align with new environment variable names and improve clarity.
- Updated tests to reflect changes in configuration handling and removed tests related to the deleted `ModelServing` class.

input-sample.md

@@ -0,0 +1,56 @@
+##### Insert a new experiment run
+
+```sql
+-- Optional: remove a previous run with the same id
+DELETE FROM public.experiment_run WHERE experiment_run_id = 1001;
+```
+
+```sql
+INSERT INTO public.experiment_run
+(experiment_name, run_name, username, status, error_message, created_at,
+updated_at, bucket_name, file_name, request_data, orchestrator_response_data)
+VALUES(
+	'test-experiment-name',
+	'test-run-name',
+	'test-username',
+	'ORCHESTRATOR_WAITING_PROC',
+	null,
+	now(),
+	now(),
+	'model-training',
+	'training_data.csv',
+	'{"experiment_run_id":1001,"variable_columns":["feature_a","feature_b"],"target_variable":"target","bucket_name":"model-training","file_name":"training_data.csv","line_separator":",","decimal_separator":".","train_size":80,"shuffle":true,"model_name":"Linear Regression","model_type":"linear_regression","data_model_kwargs":{},"model_kwargs":{},"opt_params":{},"model_metadata":{"schemas":{"components":{"schemas":{}}}}}',
+  null
+);
+```
+
+##### Upload the input dataset to MinIO
+
+```bash
+mc cp input_dataset.csv suse/model-training/training-sample-dataset-1001.csv
+```
+
+##### Temporal input payload sample
+
+Keys match `TrainModelParams.from_dict` in `model_manager/utils/models/train_model_params.py`: every field passed to `_check_none` must be present; `model_metadata` must be non-empty for `validate_business_rules()`. Omit optional keys (`date_column`, `date_format`, `random_state`, `val_file_name`, `model_id`) when defaults or `None` apply.
+
+```json
+{
+  "experiment_run_id": 1001,
+  "variable_columns": ["feature_a", "feature_b"],
+  "target_variable": "target",
+  "bucket_name": "model-training",
+  "file_name": "training-sample-dataset-1001.csv",
+  "line_separator": ",",
+  "decimal_separator": ".",
+  "train_size": 80,
+  "shuffle": true,
+  "random_state": 42,
+  "model_name": "test-runtime-linear-regression-model",
+  "model_type": "linear_regression",
+  "model_id": 1001,
+  "data_model_kwargs": {},
+  "model_kwargs": {},
+  "opt_params": {}
+}
+```