### Is there an existing issue for this?

- [X] I have searched the existing issues

### Feature description

Basically we want to only run the lambda when an insert is occurring in DynamoDB.
I tested using Dynobase deleting a record and the lambda still triggered.

```
resource "aws_lambda_event_source_mapping" "event-log" {
	event_source_arn  = aws_dynamodb_table.event-log.stream_arn
	function_name     = module.main.lambda-arn
	starting_position = "LATEST"
	enabled = true # change to false when truncating the table in localstack
	maximum_retry_attempts = 1 # limit retry on failure to 1 for now

	# https://dev.to/aws-builders/filtering-dynamodb-streams-before-lambda-p5p
	filter_criteria { # Doesn't seem to work on LocalStack for now
		filter {
			pattern = jsonencode({
				body = {
					eventName : ["INSERT"]
				}
			})
		}
	}
}
```


### 🧑‍💻 Implementation

_No response_

### Anything else?

 https://dev.to/aws-builders/filtering-dynamodb-streams-before-lambda-p5p
return fn(*args, strict_slashes=False, **kwargs)
EXEC_MUTEX = threading.RLock()
DO_USE_DOCKER = None
JSON_START_CHAR_MAP = {
    list: ("[",),
    tuple: ("[",),
    dict: ("{",),
    str: ('"',),
    bytes: ('"',),
    bool: ("t", "f"),
    type(None): ("n",),
    int: ("0", "1", "2", "3", "4", "5", "6", "7", "8", "9"),
    float: ("0", "1", "2", "3", "4", "5", "6", "7", "8", "9"),
}
POSSIBLE_JSON_TYPES = (str, bytes)
JSON_START_TYPES = tuple(set(JSON_START_CHAR_MAP.keys()) - set(POSSIBLE_JSON_TYPES))
JSON_START_CHARS = tuple(set(functools.reduce(lambda x, y: x + y, JSON_START_CHAR_MAP.values())))
LAMBDA_EXECUTOR = lambda_executors.AVAILABLE_EXECUTORS.get(
    get_executor_mode(), lambda_executors.DEFAULT_EXECUTOR
)
IAM_POLICY_VERSION = "2012-10-17"
CHECK_HANDLER_ON_CREATION = False
class LambdaRegion(RegionBackend):
    
    lambdas: Dict[str, LambdaFunction]