DBMON-4720 Part 1: Deprecate instance_config in database_metrics

[azhou-datadog]

What does this PR do?

This PR deprecates usage of instance_config in favor of SQLServerConfig in database_metrics.
This is part 1 of DBMON-4720, a later PR will address the core of the ticket to make all database metrics configurable.

Motivation

Prevent passing instance_config unnecessarily down to SqlserverDatabaseMetricsBase objects, when it can all be handled in the initial configuration of SQLServerConfig.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.54%. Comparing base (0c4e6a0) to head (04a50c9).

Additional details and impacted files

Flag	Coverage Δ
activemq	?
cassandra	?
hive	?
hivemq	?
hudi	?
ignite	?
jboss_wildfly	?
kafka	?
presto	?
solr	?
sqlserver	91.08% <100.00%> (+9.19%)	⬆️

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[github-actions]

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