chore: inject newlines to improve readability of just otel-stream output

[deniseli]

Part 3 of #2020

This PR injects newlines between blocks in just otel-stream's docker container output. We should ideally add color + bolding to this as well, which can be done by piping to a very similar sed command, but moving forward without that for now to save time.

Example snippet of the output:

Metric #2
Descriptor:
     -> Name: rpc.server.response.size
     -> Description: Measures size of RPC response messages (uncompressed).
     -> Unit: By
     -> DataType: Histogram
     -> AggregationTemporality: Cumulative

HistogramDataPoints #0
Data point attributes:
     -> rpc.grpc.status_code: Int(0)
     -> rpc.method: Str(Ping)
     -> rpc.service: Str(xyz.block.ftl.v1.VerbService)
     -> rpc.system: Str(grpc)
StartTimestamp: 2024-07-16 00:02:17.426033 +0000 UTC
Timestamp: 2024-07-16 00:02:37.427409 +0000 UTC
Count: 1
Sum: 0.000000
Min: 0.000000
Max: 0.000000

ExplicitBounds #0: 0.000000

ExplicitBounds #1: 5.000000

ExplicitBounds #2: 10.000000