Remove the schema config from flags and use only config file

[gouthamve]

Right now for setting the schema config, there are a ton of flags like:

dynamodb.daily-buckets-from, dynamodb.base64-buckets-from, dynamodb.v4-schema-from,....... dynamodb.use-periodic-tables, dynamodb.periodic-table.from, etc.

This is confusing and can be better served by the config file which is cleaner and clearer:

      - from: "2019-02-13"
        chunks:
            period: 168h
            prefix: dev_chunks_
        index:
            period: 168h
            prefix: dev_index_
        object_store: gcs
        schema: v9
        store: gcp-columnkey
      - from: "2019-02-24"
        chunks:
            period: 168h
            prefix: dev_chunks_
        index:
            period: 168h
            prefix: dev_index_
        object_store: gcs
        schema: v9
        store: bigtable-hashed
      - from: "2019-03-05"
        chunks:
            period: 168h
            prefix: dev_chunks_
        index:
            period: 168h
            prefix: dev_index_
        object_store: gcs
        schema: v10
        store: bigtable-hashed

Further, you can set more things via the config file than flags. I initially set out to rename the dynamodb prefixes, but then realised its better to totally remove these flags and only allow it to be set via config file.

[bboreham]

Might be a good time to support 1w as an alternative to 168h