Dynamic stream config has been buggy, and in hindsight, we don't need
it.

We need:
- the ability to refresh stream config periodically
- the ability to match regex stream names keys in stram config against
  requested stream names

We don't necessarily need to fetch a specific stream config from
stream_config_uri at runtime. We can simply fetch all of the
stream configs from stream_config_uri at initialization, and
then if configured, periodically re-fetch from stream_config_uri.

This patch:
- Removes support for dynamic_stream_config,
  stream_config_recache_on_expire, and stream_config_precache_list

- Removes support for templated stream_config_uri.
  We don't need this anymore if we don't request
  specific streams from stream_config_uri.

- Removes CachedMap and use of node-cache to look up and
  cache stream configs at runtime.

- Adds a new StreamConfigs class that implements the same API as
  CachedMap, except that the lookup functions are no longer async.

- When streams are looked up by regex, the cached stream config
  will be mutated to include an entry for the match.
  This keeps previous behavior where dynamically looking up a
  regex matched stream config would have that stream config cached
  under that stream name key.

- Removes use of bluebird Promises. Most use the async sugar anyway,
  only a test still used bluebird, and native Promise is fine.

Behavior changes:
- A failed re-fetch after stream_config_ttl will not flush
  previously fetch stream configs. The previously fetched stream
  configs will be used until the next successful re-fetch.
  In the previous version, dynamic stream config would take care of
  this, as if a stream config wasn't cached, it would be attemted to
  be cached the next time it was needed.

Bug: T326002
Change-Id: I9787a1c670e3d1b6f4a58e15d3dca3fb66a1558b