feat: add test coverage for hot tier

[vishalkrishnads]

This PR adds test coverage for Hot Tier, which was added in #852. The following tests are being added:

Endpoint tests

1. PUT /hottier for standalone deployment - should fail, as hot tier is enabled only for distributed
2. PUT /hottier for a stream which does not exist - should fail
3. PUT /hottier for existing stream with time partition - should fail
4. PUT /hottier for a stream with huge size (say 500 GB) - should fail because of validation failure, as disk usage should be below 80% of total disk space
5. PUT /hottier for stream with existing hot tier - increase size, should be successful
6. PUT /hottier for stream with existing hot tier - reduce size, should fail
7. GET /hottier for a stream which does not exist
8. DELETE /hottier for a stream which does not exist

Logical tests

1. create stream, ingest data for a duration, set hot tier, wait for 2-3 mins to see if all data is available in hot tier
2. create stream, ingest data, query get count, set hot tier, wait for 2-3 mins, query again get count, both counts should match
3. create stream, put hot tier, ingest data for a duration, wait for 2-3 mins to see if all data is available in hot tier
4. create stream, ingest data for a duration, call GET /logstream/{logstream}/info to get the first_event_at field. Then set hot tier, wait for 2-3 mins, call GET /hottier to get oldest entry in hot tier & assert both are equal.