rename "AVRO_SCHEMA_ID" to "SCHEMA_ID"

[agavra]

Now that schema registry supports types beyond just AVRO (and also pluggable types) it makes sense to rename AVRO_SCHEMA_ID to SCHEMA_ID so that we don't get things like:

ksql> CREATE STREAM json WITH(KAFKA_TOPIC='json', VALUE_FORMAT='json');
ksql> DESCRIBE EXTENDED JSON;

Name                 : JSON
Type                 : STREAM
Key field            :
Timestamp field      : Not set - using <ROWTIME>
Key format           : KAFKA
Value format         : JSON
Kafka topic          : json (partitions: 1, replication: 1)
Statement            : CREATE STREAM JSON (F1 STRING) WITH (AVRO_SCHEMA_ID=2, KAFKA_TOPIC='json', VALUE_FORMAT='json');

 Field   | Type
-------------------------------------
 ROWTIME | BIGINT           (system)
 ROWKEY  | VARCHAR(STRING)  (system)
 F1      | VARCHAR(STRING)
-------------------------------------

[big-andy-coates]

Likewise: #4656