Vendor-specific database attributes that are also used in metrics should be moved out of database/spans.yaml

[trask]

Vendor-specific database attributes that are also used in metrics should be moved out of database/spans.yaml, e.g.

semantic-conventions/model/database/spans.yaml

Lines 88 to 103 in b780f48

	- id: db.mssql
	type: span
	extends: db.sql
	brief: >
	Attributes for Microsoft SQL Server
	attributes:
	- ref: db.namespace
	sampling_relevant: true
	brief: The name of the database, fully qualified within the server address and port.
	note:
	When connecting to a default instance, `db.namespace` SHOULD be set to the name of
	the database. When connecting to a [named instance](https://learn.microsoft.com/sql/connect/jdbc/building-the-connection-url#named-and-multiple-sql-server-instances),
	`db.namespace` SHOULD be set to the combination of instance and database name following the `{instance_name}.{database_name}` pattern.
	For commands that switch the database, this SHOULD be set to the target database (even if the command fails).
	examples: ["instance1.products", "customers"]

[trask]

and type changed from span to attribute_group